JPH07244014A - Pollution degree-measuring apparatus for article surface - Google Patents

Abstract

PURPOSE:To simply measure pollution degree of the surface of an object to be measured without using organic solvent by spraying a compressed gas to the surface of the object to be measured, removing chargeable particles, and measuring a charge amount. CONSTITUTION:A contact terminal 5 is brought into contact with a sample component 2, the both are charged, and particles 5 are adhered to the surface of the component 2. They are introduced into a Faraday cage 1, compressed air 10 is sprayed, and only the particles 5 are blown away by a lower wire net 4. Then, an opposite charge amount Q of equal amount to that removed by the particles 5 is retained at the component 2. Thus, the charge amount removed by the removed particles 5 can be indirectly measured. The amount Q is obtained by measuring a potential V across a capacitor (having an electrostatic capacity C) 8 connected to the cage 1 and obtaining it by Q=CV. This method does not use organic solvent, and can obtain a much lower cost a apparatus when compared with a spectral type analyzer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an article surface contamination degree measuring apparatus suitable for measuring the degree of contamination of a small article.

[0002]

2. Description of the Related Art Conventionally, chlorine-based organic solvents such as Freon (particularly CFC-113), carbon tetrachloride, trichloroethylene, and 1,1,1-trichloroethane have been frequently used as cleaning liquids for metal parts. However, these solvents are internationally required to be regulated or discontinued as carcinogens or ozone depleting substances. Therefore, at the production site, we are moving to a new cleaning process that does not use these regulated solvents.

Along with this, it is necessary to evaluate the degree of simple cleaning of parts that have passed a new cleaning process.
The methods for evaluating the degree of surface degreasing and cleaning of metal working parts, which are mainly small in size and complicated, can be roughly classified into an indirect method and a direct method. A typical indirect method is a solvent having a very high extraction ability for fats and oils, and there is a method of completely extracting residual fats and oils on the surface and quantitatively evaluating it. This method has the advantages that it is simple, allows highly accurate evaluation, and is not affected by the shape of the parts. However, since the extractable solvent is limited to a chlorine-based organic solvent such as carbon tetrachloride, it is becoming difficult to implement it at the production site due to the regulation of the use of the chlorine-based organic solvent.

Direct methods include spectroscopic methods such as Auger electron spectroscopy and FT-IR. However, since the measuring device is large and expensive and lacks in simplicity, it is difficult to use it at a production site. there were.

[0005]

As described above, the conventional surface degreasing and cleaning degree evaluation apparatus is a simple apparatus for measuring the surface contamination degree of articles other than the solvent extraction method for small and complicated metal parts. There was a problem saying that there was no.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an apparatus for measuring the surface contamination level of an article, which can easily measure the contamination level of the surface of a non-measurement object without using an organic solvent. And

[0007]

In order to achieve the above object, the present invention provides a first method for spraying a compressed gas onto the surface of an object to be measured which is in contact with a chargeable particle to remove the particle. And a second means for measuring the degree of contamination of the surface of the object to be measured by measuring the charge amount of the particles removed from the object to be measured. A measuring device is provided.

Here, the compressed gas is preferably air, or a mixture of air and an inert gas such as argon, from the viewpoint of easy handling of the entire apparatus. Further, it is desirable that the charged particles have a resin coating centered on a metal such as Fe because the surface of the charged particles is protected because the measurement sensitivity can be increased.

[0009]

EXAMPLES Details of the present invention will be described with reference to examples. FIG. 1 shows a surface contamination degree measuring device used in the examples. 1
Is a metal Faraday cage that serves as the main body of the measurement unit. Inside this, a conical cavity 9 is formed in connection with the nozzle 6 for blowing out the compressed air 10. 3 is a wire mesh holder for holding a sample part 2 as an object to be measured,
Cavity 9 electrically connected to Faraday cage 1
Is formed at the exit of. Reference numeral 4 is a wire net for receiving the electric charge of the contact particles 5 blown off.

The measurement principle will be described below with reference to FIG. When the contact particles 5 and the sample part 2 are brought into contact with each other, both are charged and the contact particles 5 adhere to the surface of the part. When these are placed in a Faraday cage 1 and compressed air 10 is blown, and only the contact particles 5 are blown off by the lower wire net 4, the sample part 2
, The amount Q of charges opposite to that which the contact particles 5 have carried away remains. As a result, it is possible to indirectly measure the amount of charge carried away by the removed contact particles 5. The amount of charge Q is the capacitor (electrostatic capacity C) connected to the Faraday cage 8
The electric potential V at both ends of is measured to obtain Q = CV.
Here, from the Faraday cage 1 and the nozzle 6 to the first
In addition, the wire mesh 4, the capacitor 8 and the above-mentioned measurement system for calculating the charge amount Q from the result of measuring the voltage across the wire mesh 4 and the capacitor 8 constitute the second means.

An O-ring (oxygen-free copper, outer diameter 8.0 mm x inner diameter), which is one of the components of the anode for the magnetron, is actually used.
Using the surface contamination degree measuring device, the cleaning degree was evaluated by using the measurement oil (mineral oil) adhered to 7.2 mm, thickness 0.8 mm) as the object to be measured.

The conditions for cleaning the O-ring are as follows. (1) Cleaning conditions a. Cleaning solution: Paraffin-based and naphthene-based mixed solvent b. Cleaning conditions: 50 ° C, ultrasonic wave x 2 minutes, 100 ° C
× 2 minutes drying (2) Cleaning degree evaluation conditions a. Contact particles: Fe particles (acrylic resin coated product) b. Its particle size: 50-100 μm c. Total weight of the particles: 10 g d. Blow time: 30 seconds e. Number of sample parts: 5 Fig. 2 shows the result of quantifying the residual oil content by carbon tetrachloride extraction-infrared spectroscopic analysis of the value of the charge amount obtained with this surface pollution degree measuring device and the sample washed under the same conditions. Show.

In FIG. 2, "unwashed" means that the object to be measured has not been washed at all, "washed product" means that the product has been washed and dried by the method described above, and "conventional product" means that in the actual production process. It is a result about what was washed with 1,1,1-trichloroethane three-tank type washing device.

From the above results, there is a correlation between the amount of charge and the amount of residual oil, and the amount of residual oil remaining on the surface of the object to be measured can be measured with the same high accuracy as in infrared spectroscopy. In addition, since the device itself does not require optical parts, it is possible to provide a device that is smaller in size and much cheaper than the spectroscopic analyzer. Furthermore, it is possible to easily evaluate the cleaning degree of a metal part having a small and complicated shape as in the solvent extraction method.

The present invention is not limited to the above embodiments, but can be implemented in various modifications as follows. Even if the object to be measured is a rubber product other than the O-ring, a plastic product, or a metal part having a relatively small shape such as a connector pin, it can be measured in the same manner as in the above embodiment.

It is desirable that the contact particles are sufficiently small with respect to the object to be cleaned and exhibit a large amount of charge when brought into contact with parts. The Fe particles coated with the acrylic resin (particles used in the above examples) Diameter: 50-100 μm)
Etc. can be used.

Furthermore, in the above-mentioned embodiment, the degree of contamination after washing the object to be measured is measured, but the degree of contamination in any state can be measured by the apparatus of the present invention, for example, the object to be measured before washing. It is also possible to measure the degree of surface contamination of.

[0018]

EFFECT OF THE INVENTION The cleaning degree evaluation method of the present invention compares particles with a spectroscopic analyzer by mixing and contacting the particles with the object to be cleaned and measuring the charge amount of the particles, without using an organic solvent. Thus, it is possible to provide a device that is very inexpensive.

[0019]

[Brief description of drawings]

[0020]

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

[0021]

FIG. 2 is a diagram illustrating an embodiment of the present invention.

[0022]

[Explanation of symbols]

 1 Faraday cage 2 Sample parts 3 Wire mesh holder 4 Wire mesh 5 Particles blown off 6 Nozzle

Claims (1)

[Claims] 1. A first method for spraying a compressed gas onto a surface of an object to be measured which is brought into contact with chargeable particles to remove the particles.
And the second means for measuring the degree of contamination of the surface of the object to be measured by measuring the charge amount of the particles removed from the object to be measured. Degree measuring device.