JP2004347419A - Optical dimension measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical dimension measuring apparatus for carrying a heated wire, such as a hot rolling wire and a wall rolling wire, and improving precision in dimension measurement. <P>SOLUTION: The optical dimension measuring apparatus A has a measuring section comprising a through hole 11, where a hot wire W is inserted to the center of a plate 10; and an emission section 20 and a light reception section 30 that are arranged oppositely while pinching the through hole 11. The emission section 20 has a light source 21 that has a small amount of variation in emission intensity and has low coherence properties. The optical system of the light reception section 30 has an image-forming lens 33 and a pin hole 34 arranged at the focal distance. Then, the interval between the hot wire W and the image-forming lens 33 is two times larger than the focal distance of the image-forming lens 33. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical dimension measuring device. More specifically, the present invention relates to an optical dimension measuring apparatus capable of accurately measuring the dimensions of a heated wire such as a hot rolled wire or a hot rolled wire while transporting the wire.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in precision rolling of a wire represented by a steel wire, the diameter of the wire is measured by an optical dimension measuring device to control its dimension.
[0003]
As such a dimension measuring device, for example, as shown in FIGS. 6 and 7, a light emitting portion having a laser diode (LD) 121 as a light source with a wire W inserted through a through hole 11 provided in the center of a plate 10 interposed therebetween. An optical system 120 and a light receiving unit 130 having a CCD line sensor 131 for sensing light from the light emitting unit 120 are arranged opposite to each other on the plate 10, namely, a light emitting unit optical system 122 and a light receiving unit optical system 132 An optical measuring device A ′ having a measuring section is known.
[0004]
In FIG. 7, reference numeral 123 denotes a condenser lens that converts light from the laser diode 121 into parallel light, and reference numeral 124 denotes heat-resistant glass with a slit that converts parallel light from the condenser lens into sheet-like parallel light L. Reference numeral 133 denotes a heat-resistant glass with a slit for transmitting the sheet-like parallel light L, and reference numeral 134 denotes an imaging lens.
[0005]
The measurement of the dimension of the rolled wire W, that is, the diameter of the rolled wire W by the optical measuring device A ′ is performed as follows.
[0006]
When the light from the light emitting unit 120, more specifically, the light from the laser diode 121 is received by the CCD line sensor 131, the amount of light received by the CCD line sensor 131, as shown in FIG. The part outside the shadow gradually increases. Therefore, the diameter of the rolled wire W can be measured by processing the amount of light received by the CCD line sensor 131 with an appropriate threshold value and measuring the width of a portion below the threshold value.
[0007]
However, as shown in FIG. 7, the light from the laser diode 121 is emitted as a sheet-like parallel light L after starting from the point O once collected by the condenser lens 123. Therefore, the wave-like variation of the emission intensity of the laser diode 121 is enlarged and output.
[0008]
FIG. 8 shows the light receiving intensity at the boundary between the light and dark portions when the irradiation light from the light emitting unit 120 is received by the CCD line sensor 131. From FIG. 8, it is understood that a variation in the amount of received light due to a variation in the emission intensity appears at the boundary portion, and therefore the boundary of the rolled wire W cannot be identified by a mere threshold processing. In other words, it is understood that the dimensional measurement of the rolled wire W cannot be performed with high accuracy by simple threshold processing.
[0009]
In addition, in dimension measurement of a heating wire such as a hot-rolled wire and a warm-rolled wire, there is a refractive index distribution, that is, a fluctuation phenomenon caused by a temperature distribution around the heating wire. In the case where such a refractive index distribution (fluctuation phenomenon) exists, when dimensional measurement is performed using the laser diode 121, the irradiation light from the laser diode 121 has high coherence, so that interference occurs in the irradiation light itself. As a result, the intensity of light received by the light receiving unit 130 varies, which promotes a decrease in the accuracy of dimension measurement. Further, in dimension measurement of a heated wire such as a hot rolled wire or a warm rolled wire, a distance between a measurement system and an object to be measured is required to some extent, so that a measurement error due to a fluctuation phenomenon tends to increase.
[0010]
[Problems to be solved by the invention]
The present invention has been made in view of the problems of the related art, and provides an optical dimension measuring apparatus capable of accurately measuring the dimensions of a hot-rolled wire or a hot-rolled wire while transporting the heated wire. It is aimed at.
[0011]
[Means for Solving the Problems]
The optical dimension measuring apparatus of the present invention includes a through hole through which a member to be measured is inserted at the center of the plate, and a measuring unit including a light emitting unit and a light receiving unit that are arranged to face each other with the through hole interposed therebetween. The light-emitting unit has a light source with a small variation in emission intensity and low coherence, and the optical system of the light-receiving unit has an imaging lens and a pinhole or a slit disposed at a focal length of the imaging lens. The distance between the member to be measured and the imaging lens is twice the focal length of the imaging lens.
[0012]
In the optical dimension measuring device of the present invention, it is preferable that the light source is a light emitting diode.
[0013]
Further, in the optical dimension measuring apparatus of the present invention, it is preferable that the focal length of the imaging lens is 10 times or less the measurement accuracy within a range of ± 20 nm of the fundamental wavelength of the light emitting diode.
[0014]
Furthermore, in the optical dimension measuring device of the present invention, it is preferable that the diameter of the pinhole or the width of the slit be 10 times or less the measurement accuracy.
[0015]
[Action]
Since the optical dimension measuring device of the present invention is configured as described above, the measurement can be performed with high accuracy without being affected by the fluctuation phenomenon that occurs when measuring a heated wire such as a hot rolled wire or a warm rolled wire. I can do it.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described based on embodiments with reference to the accompanying drawings, but the present invention is not limited to only such embodiments.
[0017]
1 and 2 show an optical dimension measuring device according to an embodiment of the present invention. In FIGS. 1 and 2, the same or similar components as those in FIGS. 6 and 7 are denoted by the same reference numerals, and description thereof is omitted.
[0018]
As shown in FIG. 2, the optical system of the optical dimension measuring apparatus A emits light with a light source 21 and a light emitting unit 20 having a light emitting unit optical system 22 for parallelizing the irradiation light from the light source 21 and a wire W. The light receiving unit 30 includes a light receiving unit optical system 32 opposed to the unit optical system 22 and a light receiving unit 30 having a light receiving element 31 that receives light from the light receiving unit optical system 32.
[0019]
As the light emitting section 20, a light source 21 having a small variation in light emission intensity and low coherence, for example, a high brightness light emitting diode (LED) is used.
[0020]
As shown in FIG. 2, the light emitting unit optical system 22 includes a first cylindrical lens 23 and a second cylindrical lens 24 provided orthogonal to the first cylindrical lens 23. Here, the combination of the first cylindrical lens 23 and the second cylindrical lens 24 orthogonal to the first lens is used to efficiently irradiate the luminous flux to the wire W to be measured as line light, and to receive light by the light receiving unit 30. This is because by increasing the parallelism in the above, errors in the bright and dark portions of the wire W to be measured are reduced, and the measurement accuracy is improved.
[0021]
As shown in FIG. 2, the light receiving unit optical system 32 has an imaging lens 33 and a pinhole (or slit) 34 provided at a focal position of the imaging lens 33. Here, the distance between the imaging lens 33 and the wire W to be measured is set to twice the focal length of the imaging lens 33. This is to minimize the measurement error due to the fluctuation phenomenon.
[0022]
The imaging lens 33 has a focal length that is 10 times or less the measurement accuracy (for example, ± 30 μm) within the range of the light emission fundamental wavelength of ± 20 nm of the high brightness light emitting diode used as the light source 21.
[0023]
The diameter of the pinhole 34 (its width in the case of a slit) is set to be 10 times or less the measurement accuracy. For example, if the measurement accuracy is ± 30 μm, the diameter of the pinhole is 300 μm or less.
[0024]
The light receiving element 31 is, for example, a CCD line sensor and is disposed at an image forming position of the image forming lens 33. The CCD line sensor has an element size and number of 10 μm × 10 μm and 4096 pieces, a scanning cycle of 135 μsec, and a resolution of 14 μm.
[0025]
Here, the light source 21, the first cylindrical lens 23, the second cylindrical lens 24, the imaging lens 33, the pinhole 34, and the light receiving element 31 are arranged on the same optical axis C as shown in FIG. .
[0026]
Next, the principle of measurement by the optical dimension measuring apparatus A having such a configuration will be described with reference to FIG.
[0027]
(1) The irradiation light from the light source 21 is condensed on the XZ plane by the first cylindrical lens 23 and is converted into light parallel to the XZ plane.
[0028]
(2) The irradiation light that has passed through the first cylindrical lens 23 and has been made parallel to the XZ plane is condensed on the XY plane by the second cylindrical lens 24 to be light L parallel to the XY plane, and is measured as an object L (wire material). W).
[0029]
(3) The parallel light L that has passed through the measurement target (wire W) and reached the imaging lens 33 is condensed at the focal position by the imaging lens 33 and transmitted through the pinhole 34. In this case, of the irradiation light, light that is not parallel to the XY plane cannot pass through the pinhole 34, so that light generated by the fluctuation phenomenon is blocked.
[0030]
(4) The irradiation light transmitted through the pinhole 34 forms an image on the light receiving element 31. Since the influence of the fluctuation phenomenon is excluded from the formed image, the variation at the boundary between light and dark is reduced.
[0031]
As described above, according to the optical dimension measuring apparatus A of this embodiment, the dimension of the hot wire or the warm wire can be accurately measured by eliminating the influence of the fluctuation phenomenon.
[0032]
【Example】
Next, the present invention will be described more specifically based on more specific examples.
[0033]
The optical dimension measuring device (light source: blue LED; CCD: scanning cycle: 135 μsec, resolution: 14 μm) of the embodiment is used to coldly measure the dimensions of 11.85 mmφ elema material (trade name of Daido Steel Co., Ltd.). The test was carried out at a hot time (800 ° C.), and the results are shown in FIG. In addition, the width at the boundary between the bright and dark portions of the CCD captured image during the hot time was 65 μm.
[0034]
From FIG. 4, it can be seen that the variation (3σ) is 28 μm both in the cold state and in the hot state. Therefore, in the dimension measurement by the optical dimension measuring device of the embodiment, it is understood that the adverse effect on the measurement due to the fluctuation phenomenon is eliminated. Further, it was confirmed that the difference in measurement between the time of cold and the time of hot was almost equal to the difference in thermal expansion. Therefore, according to the optical dimension measuring device of the embodiment, it was confirmed that the dimension measurement of the hot wire and the warm wire could be accurately performed.
[0035]
Comparative Example Dimensional measurement of an elema material having a diameter of 11.85 mmφ (trade name of Daido Steel Co., Ltd.) was performed at a cold time and a hot time (900 ° C.) by the optical size measuring device of the conventional example, and the results were obtained. As shown in FIG. In addition, the width at the boundary between the bright and dark portions of the CCD captured image during the hot time was 296 μm.
[0036]
From FIG. 5, it can be seen that the variation (3σ) at the time of cold is 28 μm, while the variation (3σ) at the time of hot is 128 μm. Therefore, in the dimension measurement by the optical dimension measuring device in the comparative example, it is understood that the adverse effect on the measurement due to the fluctuation phenomenon is remarkably exhibited.
[0037]
【The invention's effect】
As described in detail above, according to the optical dimension measuring apparatus of the present invention, the dimensions can be accurately measured without being affected by the fluctuation phenomenon that occurs when measuring the dimensions of a heated wire such as a hot rolled wire or a warm rolled wire. An excellent effect that measurement can be performed is obtained.
[Brief description of the drawings]
FIG. 1 is a schematic view of an optical dimension measuring device according to an embodiment of the present invention.
FIG. 2 is a schematic diagram of an optical system of the optical dimension measuring device.
FIG. 3 is an explanatory diagram of functions of the optical system.
FIG. 4 is a graph of a measurement result of the example.
FIG. 5 is a graph of a measurement result of a comparative example.
FIG. 6 is a diagram corresponding to FIG. 1 of a conventional optical dimension measuring device.
FIG. 7 is a diagram corresponding to FIG. 2;
FIG. 8 is a graph showing the light reception intensity at the boundary between light and dark when irradiation light from a laser diode is received by a CCD line sensor.
[Explanation of symbols]
REFERENCE SIGNS LIST 10 plate 11 through hole 20 light emitting section 21 light source 22 light emitting section optical system 23 first cylindrical lens 24 second cylindrical lens 30 light receiving section 31 light receiving element, CCD line sensor 32 light receiving section optical system 33 imaging lens 34 pinhole (slit)
A Optical measuring device L Parallel light W Hot rolled wire, warm rolled wire

Claims (4)

A through-hole through which a member to be measured is inserted into the center of the plate, and a measuring unit including a light-emitting unit and a light-receiving unit that are arranged to face each other with the through-hole interposed therebetween;
The light-emitting unit has a light source with less variation in emission intensity and low coherence,
The optical system of the light receiving section has an imaging lens and a pinhole or slit disposed at the focal length thereof,
An optical dimension measuring device, wherein a distance between the member to be measured and the imaging lens is twice as long as a focal length of the imaging lens. 2. The optical dimension measuring device according to claim 1, wherein the light source is a light emitting diode. 3. The optical dimension measuring apparatus according to claim 2, wherein the focal length of the imaging lens is set to be 10 times or less the measurement accuracy within a range of ± 20 nm of the fundamental wavelength of the light emitting diode. 2. The optical dimension measuring apparatus according to claim 1, wherein the diameter of the pinhole or the width of the slit is set to 10 times or less of the measurement accuracy.

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