JPH0731939A - Cleaning evaluation method - Google Patents

Abstract

(57) [Summary] [Structure] A test piece and electrode after cleaning are placed in a bath solution, and an AC voltage is applied between them to measure the voltage between the test piece and the electrode and the voltage of the dummy resistor. Then, the amount of increase in resistance due to the deposit on the test piece is calculated from these values, and the cleaning degree is evaluated from this value. [Effect] The cleaning evaluation can be performed easily, quickly, highly accurately and quantitatively and efficiently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention measures the amount of residual oil after cleaning articles and parts contaminated with oil with cleaning water such as high-temperature pure water to evaluate on-site cleaning and a cleaning system. The present invention relates to a cleaning evaluation method for easily, accurately and efficiently setting cleaning conditions.

[0002]

2. Description of the Related Art Conventionally, in order to accurately measure the degree of cleaning, a test piece is dipped in a solvent such as carbon tetrachloride to remove the adhered oil content, and the oil content in the solvent is adjusted to the oil content concentration. There is a method of measuring with an instrument such as a gauge. However, this method is very laborious and has a drawback that it cannot be evaluated immediately.

There is also a method of measuring the contact angle of a test piece by applying water droplets to the test piece, but it is difficult to evaluate the entire surface of the piece and it takes time.

On the other hand, in the field, a mist is sprayed on the piece, and the condition (a kind of contact angle) of the water droplets is visually observed to make a qualitative judgment. However, since this method is subjective, it suffers from a lack of accuracy.

In view of the above points, an object of the present invention is to provide a cleaning evaluation method capable of performing cleaning evaluation simply, quickly, highly accurately and quantitatively and efficiently.

[0006]

The cleaning evaluation method according to the present invention has been devised to solve the above-mentioned problems, and a test piece and an electrode after cleaning are arranged in a bath liquid, and a test piece and an electrode are disposed between them. Applying an AC voltage, measuring the voltage between the test piece and the electrode and the voltage of the dummy resistance, obtaining the resistance increase due to the deposit on the test piece from these values, and evaluating the degree of cleaning from this value. It is a feature.

As the bath liquid, tap water is generally used, but an aqueous solution such as saline may be used.

[0008]

EXAMPLES Next, examples of the present invention will be specifically described.

In FIG. 1, a metal plate made of stainless steel or brass is used as an electrode (1) and a water tank (2) storing tap water.
It is placed in a hanging shape on one side of the inside and is separated from the electrode (1) (d = 50
Approximately 100 mm) apart, soak the flat plate-shaped test piece (3) after washing in tap water, and place 2
V, 5 kHz AC voltage (to prevent electrolysis)
Is applied. Voltage V between electrode (1) and test piece (3)
x and dummy resistor (4) (Ro = 300 ohm) voltage Vo
The resistance Rx1 between the electrode (1) and the test piece (3) and the resistance Rxo in the case of a clean piece obtained from these values were measured by the voltmeter, and the resistance increase due to the adhesion of the oil layer (7) The minute ΔRx is calculated by ΔRx = Rx1−Rxo. Here, the resistance between the electrode (1) and the test piece (3) is Rx =
It is calculated from Ro × Vx / Vo.

The above relationship will be verified with an electric model as shown in FIG. The total resistance Rx is represented as a parallel combined resistance of the resistance R1 of the portion where the oil layer (7) is attached and the resistance R2 of the portion where the oil is not attached. Ie

[Equation 1] When actually checking whether or not this model is correct, it becomes as shown in FIG. In this test, a flat plate test piece made of stainless steel as shown in FIG. 4 was used (width W = 50,
100, 150, 200 mm, piece height H 150 m
m, adhesion height of oil layer, that is, immersion depth x = 107 m
m). In this test, the test piece was dipped in the oil while varying the immersion depth x, and the relationship between the immersion ratio X and Rx was investigated. Each point in FIG. 3 is an experimental point, a curve is a calculated value,
These are almost in agreement.

The above test is a test in which the oil adhesion area is changed. However, even if the thickness of the oil film changes, the thickness and the resistance have a linear relationship, so that the total oil adhesion can be measured by the resistance.

In a modification of the present invention, as shown in FIG.
A cough (5) is provided between the electrode (1) and the test piece (3), and an overflow port (6) is provided on the side wall on the piece side so that the floating oil can efficiently overflow from here. As a result, accurate measurement can be performed by preventing oil from adhering to the piece when the piece is taken in and out (this oil only removes water stains, and a large amount of oil does not come out after cleaning).

Further, tap water is preferable as the bath liquid to be stored in the water tank (2), but if salt water is used at an appropriate concentration,
The measurement accuracy is further improved.

FIG. 5 shows the test results by the electric resistance measurement of the present invention, and FIG. 6 shows the test results by the conventional oil concentration measurement (both are tap water), and these tendencies are well consistent. I am doing it. In the figure, the horizontal axis represents the mounting inclination angle of the cleaning nozzle, ◯ represents the measured value, and ● represents the average value. In this measurement example, only a small amount of oil is measured, and the resistance measurement method enables highly accurate measurement.

Also, the piece is soaked in oil and pulled up, and the oil is allowed to flow down naturally (a very thin oil film is formed).
It was found that even a thickness of about 1/200 can be measured.

[0016]

According to the cleaning evaluation method of the present invention, a test piece and an electrode after cleaning are arranged in a bath solution, and an AC voltage is applied between them, and the voltage between the test piece and the electrode and the dummy resistance are applied. Voltage is measured, the resistance increase due to the deposit on the test piece is calculated from these values, and the degree of cleaning is evaluated from this value.
It can be performed with high accuracy and quantitative efficiency.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an apparatus showing an embodiment of the present invention.

FIG. 2 is a diagram of an apparatus for verifying the relationship between oil content and resistance.

FIG. 3 is a graph showing the relationship between the immersion ratio and the electric resistance.

FIG. 4 is a front view showing a test piece.

FIG. 5 is a graph showing test results by electric resistance measurement.

FIG. 6 is a graph showing test results by measuring oil concentration.

[Explanation of symbols]

 1: Electrode 2: Water tank 3: Test piece 4: Dummy resistance 5: Cough 6: Overflow 7: Oil layer

Claims (1)

[Claims] 1. A test piece and an electrode after washing are arranged in a bath solution, an AC voltage is applied between them, the voltage between the test piece and the electrode and the voltage of a dummy resistor are measured, and these are measured. A cleaning evaluation method characterized in that the increase in resistance due to deposits on the test piece is obtained from the value, and the degree of cleaning is evaluated from this value.