JP3628487B2 - Coating wire thickness measuring machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for measuring the coating thickness of a coated strand, and more particularly to an apparatus for measuring the coating thickness of a coated wire in which irregularities appear on the surface of the coating.
[0002]
[Prior art]
The following are known as devices for measuring the uneven thickness and the film thickness of the coated wire.
First, there is a non-contact type measuring machine that measures the thickness deviation using an electromagnetic sensor and an optical sensor. In this method, the position of the core wire in the coating is specified by an electromagnetic sensor, the outer diameter of the measurement object is measured by an optical sensor, and the amount of uneven thickness is measured from the deviation between the centers of the two.
[0003]
A toroid transformer to which a high frequency is applied is used for the electromagnetic sensor. When a high frequency is applied to the toroid transformer adjacent to the covered wire, a current is also generated in the core wire of the covered wire by induction, and a magnetic field is generated around the current. If multiple electromagnetic sensors are placed around the covered wire and the position of the sensor is moved so that each sensor receives a magnetic field of the same strength, the core wire of the covered wire is always located at the center of each sensor. become.
[0004]
On the other hand, a light source and a photodiode array are used for the optical sensor. The coated wire positioned between the light source and the photodiode array is illuminated with the light source to form a projected image that is displayed bright and dark, and the projected image is scanned with the photodiode array to measure the outer diameter. Since the center of the optical sensor is moved so as to coincide with the center of the core wire by the measurement of the electromagnetic sensor, the position of the projected image of the covered wire in the photodiode array corresponds to the thickness deviation of the covered wire.
[0005]
In addition, there is a contact-type measuring machine that measures the amount of uneven thickness by rotating an electromagnetic sensor in contact with a measurement object.
In addition, there is a technique for measuring by irradiating a measurement target with ultrasonic waves.
[0006]
[Problems to be solved by the invention]
However, the above devices mainly measure the plate shape or circular cross section, and when applying this technique to measure the coating thickness of epoxy strands (epoxy resin coated PC steel strands) It is difficult to measure accurately due to problems such as
[0007]
(1) Even when a non-contact type measuring machine has large irregularities on the surface of the object to be measured, it is difficult to detect the coating thickness. As a general epoxy strand, there is a core wire in which about 6 to 9 strands of about 3 to 6 mmφ are combined with an epoxy resin coating, but such a product has large unevenness on the coating surface, and has high accuracy. Measurement is not possible.
[0008]
{Circle around (2)} Since the contact-type measuring machine has a large probe of about 10 to 20 mmφ in contact with the object to be measured, it is difficult to specify and measure the internal wire from outside the coating. In particular, in the case where sand is adhered to the coating surface in order to improve the fixing property between the epoxy strand and the concrete, the probe cannot be measured because it is worn by contact with the epoxy strand.
[0009]
{Circle around (3)} Ultrasonic measuring machines can be used only when the object to be measured is planar. For a measurement object having a large unevenness on the surface, the reflected wave on the surface of the coating layer and the reflected wave on the surface of the metal element wire are not stable, and the path of ultrasonic waves is not constant, so it is difficult to measure the coating thickness.
[0010]
Therefore, the main object of the present invention is to provide an apparatus capable of measuring the coating thickness of a wire in a non-contact manner from the coating having irregularities on the surface.
[0011]
[Means for Solving the Problems]
The present invention has been made in order to solve the above-described problems. The feature of the present invention is that in a film thickness measuring machine for measuring the thickness of a coating formed on a core wire obtained by combining a plurality of strands, An electromagnetic displacement meter that is arranged around the wire and measures the distance to the core wire, a distance measuring device that measures the distance between the electromagnetic displacement meter and the wire, and a covering from the measurement results of the electromagnetic displacement meter and the distance measuring device And a means for calculating the thickness.
[0012]
Here, it is preferable to provide means for correcting the output of the electromagnetic displacement meter for the wire having the same size as the core wire of the covered wire to be measured so as to correspond to the actual distance from the displacement meter to the crown portion of the core wire. It is. The crown portion refers to a place where each strand of the wire protrudes from the sheath toward the outer peripheral side.
[0013]
The means for calculating the coating thickness can obtain the coating thickness at the crown portion of the wire from the coating by any of the following calculations.
[0014]
(1) The measurement result of the distance measuring device is subtracted sequentially from the measurement result of the electromagnetic displacement meter, and the thickness of the coating at the crown portion of the wire is obtained from the maximum point of the subtraction result that changes periodically.
[0015]
(2) The measurement result of the distance measuring device is subtracted from the measurement result of the electromagnetic displacement meter corresponding to the minimum point of the measurement result of the interval measuring device that changes periodically, and the coating thickness of the crown portion of the wire is obtained from the coating. .
[0016]
In addition, it is desirable to provide a means for correcting the measurement results of the electromagnetic displacement meter and the distance measuring device to be the same at a portion where the core wire is exposed without covering from the coated wire.
[0017]
It is preferable that a plurality of electromagnetic displacement meters and distance measuring devices arranged around the stranded wire are provided. Thereby, the film thickness of several places in a strand can be measured.
[0018]
Further, means for moving the displacement meter and the distance measuring device based on the measurement result of each electromagnetic displacement meter or the distance measuring device so that the center of the covering wire coincides with the center of each electromagnetic displacement meter and the distance measuring device. It is preferable that
[0019]
And an outer diameter measuring device for measuring the outer diameter of the wire from the sheath, the amount of change obtained by subtracting the outer diameter of the core wire from the outer diameter of the wire from the sheath obtained by the outer diameter measuring device, and the position where the coated wire is opposed to It is desirable to provide means for correcting so that the sum of the film thickness values obtained from the pair of electromagnetic displacement meters and the distance measuring device for measuring the distance coincides.
[0020]
In that case, you may apply the correction value obtained by the means to correct | amend to a pair of electromagnetic displacement meter and space | interval measuring device which measure the other opposing position of a covered wire | wire.
[0021]
Further, by correcting the timing of measurement by the outer diameter measuring instrument and the timing of measurement by each measuring means including one set of electromagnetic displacement meter and interval measuring instrument, correction is performed so that the same circumference of the wire can be measured. More preferably, it comprises means.
[0022]
In addition, as a measuring object of said apparatus of this invention, an electroconductive strand is used and a wire is more effective than the coating | cover by which an unevenness | corrugation is seen on the surface of coating | cover. The material of the coating is not particularly limited as long as it is an electrical insulator.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
First, FIG. 1 shows an outline of the overall configuration of the device of the present invention. The apparatus of the present invention uses eddy current displacement meters 11-14 (electromagnetic displacement meters) and distance measuring devices 21-24 to measure the coating thickness of the traveling epoxy strands (coating strands). A plurality of the displacement meters and the distance measuring devices are arranged on the outer periphery of the epoxy strand to be measured, and the film thickness can be measured at several places on the entire circumference of the epoxy strand. In this example, a total of four sets (interval measuring machines 11 to 14, flow displacement meters 21 to 24) are provided with one displacement meter and one interval measuring device as one set of measuring means, and the film thickness on the upper, lower, left and right sides of the epoxy strands. Can be measured.
[0024]
The arrangement of the eddy current displacement meters 11 to 14 and the distance measuring devices 21 to 24 is shown in FIG. The eddy current displacement meters 11 to 14 are arranged at appropriate intervals in the longitudinal direction of the epoxy strand S, and are arranged on the top, bottom, left and right of the epoxy strand S, respectively. Further, the distance measuring machines 21A to 24A and 21B to 24B are installed at positions corresponding to the eddy current displacement meters 11 to 14.
[0025]
Here, the eddy current displacement meters 11 to 14 include a coil to which a high frequency is applied. When a high frequency is applied to the coil, an eddy current is generated in the core wire of the epoxy strand S adjacent to the coil, thereby generating a magnetic field. As a result, since the impedance of the coil changes according to the distance from the core wire, the distance to the core wire can be measured from this.
[0026]
On the other hand, the distance measuring devices 21 to 24 include light emitting units 21A to 24A that irradiate a laser beam and light receiving units 21B to 24B that receive the laser beam, and are arranged so as to sandwich the epoxy strand S therebetween. The light emitting units 21A to 24A irradiate the laser beam in a direction orthogonal to a line connecting the eddy current displacement meters 11 to 14 and the epoxy strand S. This laser beam is scanned back and forth at high speed in the direction of the line connecting the eddy current displacement meters 11 to 14 and the epoxy strand S, a part of which is shielded by the epoxy strand S, and the rest reaches the light receiving portions 21B to 24B. From this, the distance between the eddy current displacement meters 11 to 14 and the coating surface of the epoxy strand is measured. Therefore, the thickness of the coating can be obtained by subtracting the measurement results of the distance measuring devices 21 to 24 from the measurement results of the eddy current displacement meters 11 to 14.
[0027]
In addition to the displacement meters 11 to 14 and the measuring machines 21 to 24, the device of the present invention also includes an outer diameter measuring device 1 and a linear speed meter 2 (see FIG. 1). The outer diameter measuring device 1 is disposed between the distance measuring device 11 and the distance measuring device 12, for example, and measures the outer diameter of the coated epoxy strand. The outer diameter measuring device 1 also includes a light emitting portion and a light receiving portion in the same manner as the distance measuring devices 21 to 24, and obtains the outer diameter of the epoxy strand from the range where the laser light is shielded. The linear speed meter 6 detects the traveling speed of the epoxy strand.
[0028]
The measurement data of these eddy current displacement meters 11 to 14, the distance measuring devices 21 to 24, the outer diameter measuring device 1 and the linear velocity meter 2 are all collected in the computer 3. Further, the eddy current displacement meters 11 to 14, the distance measuring device, and the outer diameter measuring device 1 are supported by a fine movement X stage 4 and a fine movement Y stage 5 for moving the whole in the X direction and the Y direction. The stages 4 and 5 are driven by motors 6 and 7, and the motors 6 and 7 are controlled by the computer 3. The computer 3 includes a keyboard 8 as an input device and a CRT 9 as an output device, and performs a process described later in the computer to determine the thickness of the epoxy strand.
[0029]
First, the eddy current displacement meters 11 to 14 are adjusted prior to the measurement of the film thickness. Normally, as shown in FIG. 3, the eddy current displacement meter is adjusted so that the output and the distance to the measurement object have a proportional relationship with respect to the planar measurement object, and this relationship is represented by a straight line 25. However, the relationship between the output of the eddy current displacement meter and the distance to the core line is a curve 26 in a measurement object having an uneven surface such as an epoxy strand. Therefore, the eddy current displacement meter is used after correcting the relationship between the output of the eddy current displacement meter and the distance to the core line so as to correspond to the actual curve. To correct, measure the distance from the eddy current displacement meter to the core wire and record the measurement result obtained from the output of the eddy current displacement meter so that the measurement result matches the measurement result. The eddy current displacement meter output correction formula is stored in the computer 3 for each product size.
[0030]
The displacement meter after the above correction is set as shown in FIG. 2, and the epoxy strand is run to measure the film thickness. This epoxy strand S has a structure as shown in FIG. This is a core wire in which a plurality of strands 15 (PC steel wires) are combined, and an epoxy resin coating 16 is applied, and irregularities are formed on the surface of the coating. When measuring the coating thickness of this epoxy strand S, the thickness of the coating is different between the groove portion 17 formed between the strands 15 and the location where each strand 15 protrudes to the outer peripheral side, Here, the latter is the crown portion 18 and the coating thickness is measured.
[0031]
To measure the film thickness, as shown in FIG. 5, the distance (L) from the displacement meter 12 to the strand 7 is measured with the eddy current displacement meter 12, and the distance between the vortex displacement meter 12 and the epoxy strand is measured with the distance measuring devices 22A and 22B. The distance (w) to the coating surface of S is measured. The film thickness (t) can be obtained by Lw. However, in order to specify the film thickness of the crown portion, the following procedure is further required.
[0032]
As shown in FIG. 2, the surface of the epoxy strand has a wavy shape that changes periodically. Therefore, the measurement result 30 of the distance measuring device shows a periodic change corresponding to the unevenness of the coating surface, as shown in FIG. On the other hand, the measurement result 31 of the eddy current displacement meter is almost constant regardless of the irregularities on the surface of the core wire. The cause of this is not clear, but it is presumed that accurate measurement is difficult because the core wire is composed of a plurality of strands and the surface is curved. Therefore, if the measurement result 30 of the interval measuring device is subtracted sequentially from the measurement result 31 of the eddy current displacement meter, a periodic waveform subtraction result 32 having an opposite phase to the measurement result 30 of the interval measuring device is obtained. The maximum point 33 corresponds to the film thickness of the crown portion.
[0033]
Note that the epoxy strands are vibrated by running. When this vibration is large, the measurement result of the distance measuring device is subtracted sequentially from the measurement result of the eddy current displacement meter as described above to cancel the fluctuation of the measurement result due to the vibration, and the maximum point of the subtraction result is the crown portion. It is necessary to judge that it corresponds to. However, when the vibration is small, the periodic waveform minimum point 34, which is the measurement result 30 of the interval measuring machine, corresponds to the crown portion. Therefore, the minimum point is determined from the measurement result 31 of the eddy current displacement meter corresponding to the minimum point 34. If the value of 34 is subtracted, the film thickness at the crown can be obtained.
[0034]
The above is the basic means for measuring the film thickness of the crown portion, but in order to measure more accurately, the following correction may be performed.
[0035]
(1) Correction at the start of measurement There is a portion where the core wire is exposed without covering at the end of the epoxy strand, and more accurate measurement can be performed by performing correction at the start of measurement using that portion. For this correction, the distance (L ₀ ) to the exposed core wire surface is measured with an eddy current displacement meter, and at the same time, the distance (w ₀ ) between the eddy current displacement meter and the exposed core wire surface is measured with a distance measuring machine. Theoretically, the two measured values should match, but the measured values may not match because there is a variation in characteristics due to the temperature history of the manufacturing process of the strands constituting the core wire. For example, the strands are heat-treated during the manufacturing process, but if there are variations in the heat treatment depending on the production lot, the permeability and conductivity of the strands will also vary. As a result, the measurement results of the eddy current displacement meter Variation occurs. Therefore, α, which is the difference between the two measurement values (L ₀ −w ₀ ), is used as a correction coefficient, and the film thickness (t) is obtained from Lw−α.
[0036]
(2) Correction during continuous measurement Even when strands of the same lot are used, variation in characteristics due to the temperature history of the manufacturing process described above is observed in the longitudinal direction of each strand. Therefore, correction is performed during measurement so that a more accurate measurement result can be obtained. In this case, the outer diameter measuring device shown in FIG. 1 is used to determine the outer diameter of the coated epoxy strand, and the film thickness obtained from a pair of electromagnetic displacement meters and a distance measuring device for measuring the corresponding position of the epoxy strand. Find the total value.
[0037]
As shown in FIG. 7, the coating outer diameter (D ₀ ) is obtained by an outer diameter measuring machine, the distance (L ₁ ) to the core wire is measured by the eddy current displacement meter 12 at the upper part of the strand, and the distance measuring devices 21A, 21B obtains the distance between the 12 and the coating surface (w _1), likewise determined distance from the displacement meter 11 in the strand lower until the core wire and (L _2), the distance (w ₂₎ of the displacement meter 11 and the coating surface. All measured values are output to the computer. Further, the outer diameter (D ₁ ) of the core wire is obtained from the specification value of the strand. Usually, the outer diameter of the strand has extremely high accuracy, so the outer diameter of the core wire (obtained from the outer diameter and the number of strands) is obtained from the specification value of the strand, and this value is input to the computer in advance. And memorize it.
[0038]
The _obtained D 0 -D ₁ of the total value of the film thickness at a position opposed to the strand by calculation _{(T 1).} At the same time, the upper film thickness t ₁ is obtained from L ₁ -w ₁ , and the lower film thickness t ₂ is obtained from L ₂ -w ₂ , and the total value (T ₂ ) of the film thicknesses at the opposing positions of the strands is ( L ₁ −w ₁ ) + (L ₂ −w ₂ ) Theoretically, both total values T ₁ and T ₂ should match, but due to the above reasons, variation is seen.
_{(D 0 -D 1) - {} (L 1 -w 1) + (L 2 -w 2)}
The calculation result is used as a correction value β, and the measurement value is corrected by the correction value β. That is, the corrected film thickness t ₁ ^{′ at the} upper portion of the strand is (L ₁ −w ₁ + β), and the corrected film thickness t ₂ ^{′ at} the lower portion is determined by (L ₂ −w ₂ + β).
[0039]
In the above description, the upper and lower sides are taken as examples of the positions where the epoxy strands face each other.
[0040]
When performing these corrections, it is preferable to move each displacement meter and the distance measuring device so that the epoxy strand is centered with respect to each eddy current displacement meter and the distance measuring device. For example, the displacement meter and the interval measurement value are moved by controlling the motors of the fine movement X stage and the fine movement Y stage so that the measurement values of the four interval measurement machines match. Thereby, the distance from each displacement meter and interval measuring machine to the epoxy strand is made the same, and measurement with less error can be expected by performing the above correction together.
[0041]
Furthermore, at the time of the “correction during the continuous measurement”, by shifting the measurement timing of each set of measurement means (vortex displacement meter and interval measuring machine: see FIG. 2B) arranged shifted in the longitudinal direction of the epoxy strand, Correction accuracy can be further improved by measuring the film thickness at a plurality of locations on the same circumference of the epoxy strand.
[0042]
The distance in the longitudinal direction between the outer diameter measuring machine 1 and each measuring means is measured in advance, and three inputs are stored in the computer. The uneven pitch P (see FIG. 4A) on the epoxy strand surface is known in advance. Accordingly, the distance between the outer diameter measuring machine and each measuring means is calculated to correspond to the pitch P, and the data measured before (after) by this pitch equivalent is measured upstream (downstream). If it is extracted from the measurement results, the film thickness on the same circumference as the position measured by the outer diameter measuring device 1 can be measured.
[0043]
For example, the outer diameter measuring machine, the first measuring means for measuring the film thickness of the upper part of the epoxy strand, and the second measuring means for measuring the film thickness of the lower part are simultaneously measured, and the measurement results are sequentially transferred to a computer. Output. In the periodic displacement obtained by the interval measuring machine of each measuring means, the interval from a certain minimum point to the adjacent minimum point corresponds to the uneven pitch on the epoxy strand surface. Therefore, if the measurement data before (after) is extracted from the data at a certain measurement time of each interval measuring machine by the amount corresponding to the pitch, data on the same circumference as the position of the epoxy strand measured by the outer diameter measuring machine can be obtained. Can do.
[0044]
In the “correction during continuous measurement”, the number of outer diameter measuring machines can be reduced by using the correction value β obtained from the measurement at a certain opposing position for the measurement at another opposing position. In order to perform the above-described “correction during continuous measurement”, an outer diameter measuring machine and a pair of measuring means for measuring the film thickness at the position where the epoxy strands face each other are required. Therefore, in principle, two outer diameter measuring machines are used to perform “correction during continuous measurement” on the upper, lower, left and right sides of the epoxy strand. However, if the correction value β obtained from the measurement of the top and bottom of the epoxy strand (opposite position with the coated wire) is also used for the measurement of the left and right (other opposed positions of the coated wire), the outer diameter measuring machine Can be reduced to one, and the cost can be reduced.
[0045]
In the above description, four sets of measuring means (eddy current displacement meter and interval measuring device) are used, but this number is not particularly limited. For example, when the device of the present invention is viewed in the axial direction of the measurement object, six sets of measuring means may be arranged so as to be positioned at the apex of a regular hexagon.
[0046]
【The invention's effect】
As described above, according to the apparatus of the present invention, it is possible to accurately measure the film thickness of a wire from a coating having an uneven surface.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of a device of the present invention.
FIGS. 2A and 2B show an arrangement of an eddy current displacement meter and a distance measuring device, in which FIG. 2A is an arrangement view seen from the axial direction of an epoxy strand, and FIG. 2B is an arrangement view seen from a direction orthogonal to the axis.
FIG. 3 is a graph showing the relationship between the output of an eddy current displacement meter and the distance to a measurement object.
FIG. 4 shows an epoxy strand, (A) is an external side view, and (B) is a cross-sectional view.
FIG. 5 is an explanatory diagram showing the measurement principle of film thickness.
FIG. 6 is a graph showing a measurement result of an eddy current displacement meter and an interval measuring device and a subtraction result of both.
FIG. 7 is an explanatory diagram showing a procedure for correcting a measurement result during continuous measurement.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Outer diameter measuring machine 2 Line speed device 3 Computer 4 Fine movement X stage 5 Fine movement Y stage 6,7 Motor 8 Keyboard 9 CRT 11-14 Eddy current displacement meter 21-24 Spacing measuring machine 21A-24A Light emission part 21B-24B Light-receiving part 15 Strand 16 Cover 17 Groove 18 Crown 25 Straight line 26 Curve 30 Measurement result of distance measuring device 31 Measurement result of eddy current displacement meter 32 Subtraction result 33 Local maximum point 34 Local minimum point

Claims (6)

In a film thickness measuring machine that measures the thickness of a coating formed on a core wire obtained by combining a plurality of strands,
An electromagnetic displacement meter disposed around the strand of the sheath and disposed away from the strand of the sheath ;
A distance measuring device for measuring the distance between the electromagnetic displacement meter and the coated strand;
Means for calculating the thickness of the coating from the measurement results of the electromagnetic displacement meter and the distance measuring device,
The electromagnetic displacement meter measures the distance from the electromagnetic displacement meter to the core wire,
The means for calculating the thickness of the coating sequentially subtracts the measurement result of the distance measuring device from the measurement result of the electromagnetic displacement meter, and the thickness of the coating at the crown portion of the wire from the maximum point of the subtraction result that changes periodically. An apparatus for measuring the thickness of a twisted strand wire, characterized in that: To coating without wire of the core wire and the same size of the covered wire to be measured, consistent with the measurement results from the electromagnetic displacement meter measured by the output of the electromagnetic displacement meter to the wire, the actual distance from the electromagnetic displacement gauge to wire 2. The coated strand film thickness measuring device according to claim 1 , further comprising means for correcting the output of the electromagnetic displacement meter based on an output correction formula of the electromagnetic displacement meter . Means for correcting the film thickness by correcting the measurement result of the electromagnetic displacement meter so that the measurement result of the electromagnetic displacement meter and the distance measuring device is the same at the portion where the core wire is exposed without the coating of the twisted wire. A coating thickness measuring device for a twisted strand wire according to claim 1. 2. The coating strand thickness measuring device according to claim 1, comprising a plurality of electromagnetic displacement meters and interval measuring devices arranged around the coating strand. Means are provided for moving the displacement meter and the distance measuring device based on the measurement result of each electromagnetic displacement meter or the distance measuring device so that the center of the covering wire coincides with the center of each electromagnetic displacement meter and the distance measuring device. A coating thickness measuring device for a twisted wire according to claim 4 . Corresponding electromagnetic displacement meter and interval measuring device are set as one set, and a plurality of sets of electromagnetic displacement meters and interval measuring devices are arranged at appropriate intervals in the longitudinal direction of the wire strands for each set,
5. The coated wire thickness measuring machine according to claim 4, wherein the same circumference of the coated wire can be measured by shifting the measurement timing of each set of measuring means for each set .

Images