JPS6321501A - Thickness measurement of coated film - Google Patents

Abstract

PURPOSE:To effect automatic and direct measurement on line in a continuous manner of coated film thickness in wet condition immediately after coating, by bringing a good electric conductor probe into contact with a coat film in process of drying. CONSTITUTION:A good electric conductor probe 8 with a sharp extreme edge available for forward and backward travels is applied with an electric voltage respecting a coated surface of a specimen 4 made of a metal sheet. By contact with a coated film 7 in accompaniment of the forward travel of the probe 8, the extreme end position of the probe 8 at the moment when a controlling member 3 formed by probe 8, coated film 7 and specimen 4 is interrupted is obtained. Thickness of the coated film 7 still in process of drying is measured by a distance 't' between the extreme end position of the probe 8 and the surface of the specimen 4. Coated film thickness in wet condition immediately after coating can be measured on line continuously, automatically and directly.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention continuously reduces the film thickness of undried paint adhering to the surface to be coated when continuously painting the surface of a plate material. Concerning how to measure.

<Prior art and its problems> Currently, when applying paint to a long strip-shaped metal plate.

A method is used in which the metal plate is transferred at high speed and coated with a coating device installed at a fixed point.

In such cases, in order to achieve the required film thickness or uniform film thickness, it is necessary to measure the coating film thickness after coating and control the coating equipment based on this measured value.
S is required.

There are two methods of determining the I film thickness after painting: a method of measuring the film J2 in a dug state after painting, and a method of measuring the film J2 in a dry state after painting. The latter method includes the method disclosed in Japanese Unexamined Patent Publication No. 55-149803, but in these methods, there is a time delay until the coating film dries, so it is difficult to control the coating equipment. This method has the drawback that it cannot be carried out quickly, and therefore, it is not possible to make the required film thickness or uniform film thickness over a fairly long area moved during this time delay.

On the other hand, in the former method, the time delay from coating to measurement can be extremely minimized, making it possible to quickly control the coating equipment.
It has the advantage of being able to significantly improve the particle size.

However, the methods disclosed so far for measuring the coating film thickness in a gradual state do not directly measure the coating film thickness in a state where the coating film is τ2 after the coating is applied. That is, JP-A-50-1
The method disclosed in Japanese Patent No. 09935 is a method for measuring paint film in a wet state, and is a method for measuring the amount of paint removed per unit time. The amount is measured and the coating film thickness is calculated from this.

However, in this method, the amount of paint consumed is measured by changes in the amount of paint in the paint tank, so accurate measurements cannot be made unless the measurement time is increased to a certain extent. Furthermore, since the measured value of the coating film thickness by this technique is an average value within the above-mentioned unit time, there are problems such as the inability to follow sudden changes in coating conditions.

<Object of the Invention> The object of the present invention is to solve the problems of the prior art described above, and to provide a method for high-speed continuous coating of conductors such as long strip-shaped metal plates.
To provide a method for continuously and automatically directly measuring on-line a paint film J1 in a swollen state after coating, in order to control the paint film thickness to a required film thickness or a uniform film thickness. It is in.

<Structure of the Invention> According to the present invention, when measuring the thickness of an undried paint applied to a material to be painted, the tip is installed so as to be movable forward and backward relative to the paint surface of the material to be painted. A voltage is applied to a sharp, highly conductive probe needle, and when the probe needle comes into contact with the paint accompanying the prefectural road, an electric circuit is formed through the probe needle, the paint, and the material to be coated. A coating film thickness measuring method is provided, characterized in that the thickness of the undried paint is measured based on the distance between the tip position of the probe needle and the surface of the material to be coated at the moment when the probe needle is closed.

An embodiment of the present invention will be described in detail below based on the drawings.

1, 2, and 3 are front cross-sectional views showing a first embodiment of a specific apparatus for implementing the coating film thickness measuring method according to the present invention, and A-A in FIG. 1, respectively. FIG. 1 is a cross-sectional view and a cross-sectional view taken along the line B--B in FIG.

As shown in FIG. 1, a strip-shaped metal plate 4, which is a material to be coated, is being transported at high speed along a backup roll 5 in the direction of an arrow 6.

The coating film thickness of the paint 7 adhering to the strip metal plate 4 is measured by the apparatus main body 1.

As shown in FIGS. 1, 2, and 3, the detection unit 2 includes a probe needle 8, a rod 9, a leaf spring 10, a bobbin 11, a moving coil 12, a permanent magnet 13, a yoke 14, and a distance meter 15. It is composed of main parts such as, and these are housed in a case 16.

The probe needle 8 is made of a rust-free and electrically conductive material, and one end of the probe needle 8 is fixed to a rod 9, and the other end has a sharp tip that determines the position of the surface of the paint 7. It is intended to explore. The rod 9 connects and supports the probe needle 8 and the bobbin 11, and transmits the back and forth movement of the bobbin 11 to the probe needle 8. The leaf spring 10 is for supporting the rod 9 and for resisting the movement of the rod 9 and applying a force that tries to keep the rod 9 at a neutral point.
The lower end of the spacer 1 is made of electrically insulating material.
It is fixed to the case 16 via 7. Both the rod 9 field and the leaf spring 10 are made of electrically conductive materials.

The bobbin 11 has a cylindrical shape with one end closed, and the central part of the closed end is fixed to the rod 9. This bobbin 11 is made of a material with poor magnetic conductivity, and a moving coil 12 is wound around its outer periphery. The moving coil 12 is used to generate magnetism by passing a "u+ current" through it, and to generate magnetic force between it and the permanent magnet 13. This is wound around the outer periphery of the bobbin 11 a required number of times. Made of insulated copper wire.Permanent magnet 13
has a rod-like shape with magnetic poles at both ends, and has an outer diameter such that there is a narrow required distance between its outer periphery and the inner periphery of the bobbin 11 (see FIG. 3). The yoke 14 is for effectively guiding magnetism around the moving coil 12, is made of a magnetically conductive material, and has a cylindrical shape with one end closed. One end of the permanent magnet 13 is fixed to the inner center of the closed end face of the yoke 14. Further, there is a narrow required interval between the outer circumference of the moving coil 12 and the inner circumference of the yoke 14.

Further, the outside of the closed end face of the yoke 14 is fixed to the case 16.

The end face of the open side of the yoke 14 is flush with the end face of the permanent magnet 13 on the non-fixed side, and this end face is located approximately at the center of the moving coil 12 in the axial direction. (See Figure 3).

As shown in FIG. 2, the distance meter 15 is fixed to a case 16 via a bracket 18. The distance meter 15 is used to know the position of the pobbin 11, that is, the position of the tip of the probe needle 8, and any type of device that can detect distance with micrometer accuracy may be used, for example, a vortex sensor. A current distance meter is used.

The case 16 has a small hole 16' formed in one surface thereof, and the tip of the probe needle 8 is projected outward from this hole 16'.

The lead wire 19 is for applying voltage to the probe needle 8, and its - end is connected to the grip spring 10, and the other end is connected to the opening control section 3, so that the voltage applied to the lead wire 19 is guided to the probe 118 via the leaf spring 10 and the rod 9. The lead wire 20 is for applying voltage to the moving coil 12, and one end thereof is connected to the moving coil 12, and the other end is connected to the control section 3. The lead wire 21 is for transmitting the detection low state of the rangefinder 15 to the control section 3.

The control unit 3 includes a resistance-voltage converter 22, as shown in FIG.
Comparator 23, R-S flip-flop 24, integrator 25
, a power amplifier 26, a timing pulse generator 27, a sample hold 28, and other main circuits.

The resistance-voltage converter 22 applies a voltage to the probe 8, detects the electrical resistance between the probe 8 and the paint 7, and outputs a voltage proportional to the resistance value. Comparator 2
3 is for comparing the output voltage of the resistance-voltage converter 22 with a reference voltage, determining and outputting it; if the output voltage value of the resistance-voltage converter 22 is larger than the reference voltage value, it is a low level, and if it is smaller, it is a low level. outputs a high level signal. R
-S flip-flop 24 is for continuing to output a high level signal once the output of comparator 23 becomes high level, and this is reset by the output of hI divider 25 becoming low level. Changes to low level output. The integrator 25 outputs a voltage signal that increases linearly with time when the output signal of the R-S flip-flop 24 is at a low level, and also outputs a voltage signal that increases linearly with time.
When the output signal No. 4 is at a high level, the increase is W and a constant signal is continued to be output. This integrator 2
5 is reset by applying a reset pulse output from the timing pulse generator 27, and the output becomes low level. The power amplifier 26 outputs the output 1 of the integrator 25.
This is to increase the power of No. 3 to be sufficient to drive the moving coil 12.

The timing pulse generator 27 generates a required pulse of 111 that rises at the moment the output signal of the R-S flip-flop 24 becomes high level, and a pulse of the required width that rises to F at the moment this pulse falls. This is to generate two pulses. The former pulse is input to the sample hold 28 as a sampling pulse, and the latter pulse is input to the h1 divider 25 as a reset pulse. The sample hold 28 is for sampling and holding the output signal of the distance meter 15, and its operation is performed by applying a sampling pulse from the timing pulse generator 27. The output signal of the sample hold 28 has a step-like waveform,
This value corresponds to the position of the surface of the paint 7.

Resistance-voltage conversion? ! Input terminal of i22, power amplifier 26
Lead wires 19, 20, and 21 are connected to the output terminal of the sample hold 28 and the input terminal of the sample hold 28, respectively. Board 4
In order to keep the paint 7 at ground potential, a well-conductive buffer is connected between the shaft of the blowroll 5 and the ground of the control unit 3 with a lead wire 29, so that the current flows between the control unit 3 and the lead wire 19. , leaf spring 10, rod 9, probe needle 8, paint 7
, the plate 4°, the backup roll 5, the riet wire 29, and the control section 3.

In FIG. 6, a voltage is applied to the moving coil 12, the probe needle 8 is pushed to the left, and the tip of the probe 8 is pushed out to the left.
This shows the moment when the probe needle 8 made contact with the surface of the desert.
Since the current flows from the to the paint 7, it is possible to detect that the tip of the probe 8 has come into contact with the surface of the paint 7 film.

<Specific Effects of the Invention> The coating film thickness measuring device which is an embodiment of the method of the present invention is constructed as described above, and the operation thereof will be explained below.

FIG. 5 is a timing chart showing the state of signals output from each part during operation, and a is the output of the integrator 25 (the applied voltage of the moving coil 12, the output of the distance meter 15, and the position of the probe 8). ), b is the resistance-voltage converter 2
C is the output of the comparator 23, d is the output of the R-S flip-flop 24, e and f are the outputs of the timing pulse generator 27, which are the sampling pulse and reset pulse respectively, g is the output of the sample hold 28, etc. 15 each
Indicates the number.

First, as shown in FIG. 5g, the integrator 25 starts an integrating operation because the signal applied to its input terminal is at a low level, and outputs a signal that increases with time to its output terminal. After this No. 13 is amplified by a power amplifier 26, it is applied to the moving coil 12 via the lead wire 20 to excite it.

When the moving coil 12 is excited, it generates a repulsive force between the permanent magnet 13 and the yoke 14, and slowly pushes the bobbin 11, rod 9, probe 8, etc. to the left. The probe needle 8 is pushed to the left, and at the moment its tip comes into contact with the surface of the paint film 7, the resistance-voltage converter 22, the lead wire 19, the leaf spring lO, the rod 9, and the probe needle 8, paint 7, board 4, backup roll 5
A current flows through the lead wire 29 and the resistance-voltage converter 22, so that a low-level signal is output to the output terminal of the resistance-voltage converter 22.

When the output of the resistance-voltage converter 22 becomes a low level as shown in FIG. 5, the output of the comparator 23 becomes a high level as shown in FIG.
-S flip-flop 24 is set and continues to output a high level signal. R-S flip-flop 2
The moment the output of 4 becomes high level, that is, the moment the probe needle 8 comes into contact with the surface of the film of paint 7, the integrator 25 stops the integration operation, the increase in the output signal becomes normal, and therefore the probe stops. The movement of the stylus 8 to the left stops. On the other hand, as shown in FIG. 5e, the timing pulse generator 27 outputs a sampling pulse at the moment the output signal of the R-S flip-flop 24 becomes high level, and as shown in FIG. 28 samples the distance signal output from the distance meter 15, holds it, and sends it to the probe needle 8.
continues to output a signal representing the position of the tip of the As shown in FIG. 5f, the integrator 25 is reset as shown in FIG. 5g by a reset pulse outputted from the timing pulse generator 27 at the moment when the sample hold 28 finishes its sampling operation, and its output is the lowest. Descend to value.

When the output signal of the integrator 25 reaches its lowest value, the repulsive force of the moving coil 12 disappears, and the probe needle 8 is pulled back to its original position by the elastic force of the leaf spring 10. At this time, the tip of the probe needle 8 is separated from the surface of the paint 7 at ++q, so as shown in FIG. becomes low level.

On the other hand, as shown in FIG. 5g, when the output of the integrator 25 becomes low level, the reset terminal of the R-S flip-flop 24 connected to it also becomes low level, the R-S flip-flop 24 is reset, and this output becomes low level. As the output of the R-S flip-flop 24 becomes low level as shown at 51'Aa, the input terminal r of the integrator 25 also becomes low level, and the integrator 25 starts integrating again. In this manner, the probe needle 8 repeatedly searches the surface position of the paint film 7 while performing push and pull operations.

At this time, the sample holder 28 outputs a stepped signal that is updated the moment the probe needle 8 comes into contact with the surface of the paint film 7, that is, a signal corresponding to the position of the surface of the paint film 7.

Therefore, it is necessary to know in advance the output value A of the sample hold 28 when no paint 7 is attached to the board 4, and the output value A of the sample hold 28 that is output from time to time when the paint 7 is attached to the board 4. By subtracting this value A from the output value B, the thickness t of the paint film 7 can be found.

As is clear from the above configuration and operation description, the paint film thickness measuring device implementing the method of the present invention accurately detects the position of the surface of the paint film 7 in a dug state using the probe needle 8. Therefore, it can be used extremely effectively when measuring the film thickness of a liquid electrically conductive paint applied to an electrically conductive material.

In the present invention, the tip of the probe comes into direct contact with the paint, but since the tip of the probe is sharp, there is no possibility that fi droplets of paint will stick to the tip, and the paint will not stick to the tip. Since the probe is moving at high speed, the tip of the probe needle is constantly washed away with paint, so there is no chance of paint drying and adhering to the tip, and it can be used stably for a long time. .

In this example, a moving coil is used to move the probe needle, but instead of the moving coil, an actuator using a piezoelectric element or the like may be used, or a moving coil may be used instead of a plate spring. Needless to say, it can perform both push and pull motions.

Furthermore, in this embodiment, the position of the probe needle is detected using a distance meter, but the position of the probe needle can be detected directly from the voltage value applied to an actuator such as a moving coil without using a distance meter. Needless to say, -11 is possible.

<Example> Examples and comparative examples of the present invention will be specifically described.

The painted cold-rolled steel plate is 1.2mm thick x 12001I
A coil having a width of 442 m and a weight of Q5 t was used.

The thickness of the coating film formed when coating the cold-rolled steel sheet described in E was adjusted so that the target thickness after drying was 30 houses.

The variation in coating film thickness after drying was investigated after five coils of coating were applied to the above-mentioned cold-rolled steel sheet.

A case where painting was carried out under the conditions described in section F, and a case where coating was performed by the method of the present invention as an example of the present invention while measuring the coating film thickness in an undried state using the coating film thickness measuring device configured in section 1, and a comparative example. The coating film thickness was measured after drying using the conventional method, and the L1 standard thickness of the coating film thickness after drying was 30.
Table 1 shows a comparison of the fluctuations from -.

In the coating film thickness measuring apparatus having the above structure according to the method of the present invention, the voltage applied to the probe was 10 V, and the speed of the probe was 0.1 mm/s.

As shown in Table 1, it can be seen that the variations in coating film thickness were reduced by half in the inventive examples compared to the comparative examples.

Table 1 <Effects of the Invention> According to the present invention, since the coating film thickness in an undried state can be directly measured, coating equipment 1Q J! ,! The deviation from the 1-1 standard thickness can be detected with an extremely small time delay, the coating equipment can be controlled quickly, and one company can achieve dramatically accurate and uniform coating. In particular, the method of the present invention is particularly effective when coating a long strip-shaped metal plate at high speed, and in this respect, the method of the present invention has great commercial value.

Since the paint film thickness measuring method according to the present invention uses a probe to which a voltage is applied, the paint film thickness measuring device used in the method of the present invention does not require large-scale equipment such as measuring the amount of fR in the paint tank. Since there is no need for maintenance, it can be extremely miniaturized and requires only 8 spins for maintenance.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a con-image arrangement for carrying out the method of the invention. Figure TS2 is a cutaway view taken along the line A--A in Figure 1. FIG. 3 is a sectional view taken along the line BB in FIG. 1. FIG. 4 is a block diagram of the control section having the configuration shown in FIG. 1. FIG. 5 is a timing chart of No. 13 output in each part of FIG. 4. FIG. 6 is a sectional view showing the structure of FIG. 1 in the m-state, that is, at the moment the probe contacts the paint. Explanation of symbols 1--paint film thickness device main body, 2--detection unit, 3--control unit, 4--band-shaped metal plate, 5--backup roll, 6--progressing direction of the band-shaped metal plate, 7 ...paint, 8...
Probe needle, 9-rod, l O... plate spring, 11-.
・Bobbin, 12-・Moving coil, 13-・Water/fire magnet, 14-・Yoke, 15-・Distance meter, 16-・Casing, 17-・・
Spacer, 18...bracket. 19.20.21.29 - Lead wire, 22 - Resistor-voltage converter, 23 - Comparator, 24 - R-S flip-flop, 25 - Integrator, 26 - Power amplifier, 27 - Timing pulse Generator, 28-... Sample hold, a... Output waveform of integrator, b... Output waveform of resistance-voltage converter, C... Output waveform of comparator, d-R-S flip-flop Output waveforms of the timing pulse generator, e and f indicate sampling pulses and reset pulses, respectively; g- Output waveforms of the sample hold FIG, 5 9''

Claims (1)

[Claims] (1) When measuring the thickness of undried paint applied to a material to be painted, a highly conductive probe with a sharp tip is installed so that it can move forward and backward relative to the paint surface of the material to be painted. The probe needle at the moment when a voltage is applied to the probe needle, and as the probe needle moves forward and comes into contact with the paint, an electric circuit formed through the probe needle, the paint, and the material to be coated is closed. A method for measuring coating film thickness, characterized in that the thickness of the undried coating is measured based on the distance between the tip position and the surface of the material to be coated.