JPH0781566B2 - Bolting method for steel materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to an improvement in a friction joint construction method using high-tensile steel bolts used for bridge dyeing and connecting steel materials of steel frame structures.

<Conventional technology> In the field construction of bridge dyeing, general steel structures, etc., due to the recent trend of larger structures, special attention is required in the conventional rivet method and welding method. The joining method using high-tensile steel bolts is often used for important parts, and the amount of use is also increasing.

In such a high-strength steel bolt joining method, the conventional rivet construction method transmits the joint stress by shearing the rivet, whereas the joining method using the high-tensile steel bolt makes a high-strength high-strength steel bolt yield point. Since the stress is transmitted by the frictional force generated by tightening up to the vicinity, the friction coefficient of the joint, which is an element of stress transmission, is an extremely important element. For this reason, regarding the handling of this type of bolted joint surface, in general, the presence of mill scale, excessive red rust, or coating film of paint will extremely reduce the friction coefficient, and eventually weaken the tightening strength, Since loosening is likely to occur even after tightening, regular re-tightening is required, so a method of removing mill scale, red rust, coating film, etc. is generally adopted by a grinder treatment or a blast treatment such as shot blasting or sand blasting. Has been done.

However, since the complete bare metal surface that has been subjected to grinder treatment or blast treatment as described above has a smaller friction coefficient than the light red rust surface that is uniformly generated and adheres to the entire surface, it is usually the atmosphere after grinder or blast treatment. It is customary to leave it for a long period of time and wait for the red rust to spontaneously occur before tightening it.

On the other hand, the actual situation in the recent industry is that there is no choice but to drastically shorten the period from the production of the material to the tightening and assembly. A method of applying seawater or a solution of sodium chloride, ammonium chloride or the like to the subsequent surface to promote rusting is adopted, and the present inventor has also previously mentioned Japanese Patent Application No. 56-175929 and Japanese Patent Application No. 56-175929. With 175930, we proposed a method of applying ferric chloride or a solution of ferric chloride mixed with nitric acid or iron nitrate and a surfactant, and the friction coefficient above that specified by the Japan Society of Civil Engineers and the Architectural Institute of Japan It has been implemented effectively because it can be obtained.

<Problems to be Solved by the Invention> However, the above-mentioned conventional methods have the following serious drawbacks. That is, in the conventional method, 1). Since it is a method of applying the rusting solution to the surface of the joint, (a). There is no problem if the surface is in a horizontal position, but in the case of an upright surface or an inclined surface, the coating solution hangs down, and the lower part often rusts, but the upper part is liable to rust due to insufficient liquid.

(B). Since oil and dirt are attached to the surface of the joining member due to bolt holes, etc., even if a temporary surfactant is added to the solution, the wettability is actually poor, uneven coating is possible, and uneven rust occurs. There was a drawback. In the conventional method, 2). (A) Because the mechanism of rusting is only due to the chemical reaction. It is governed by temperature conditions, especially in the low temperature of winter, rusting is slow and the quantity is insufficient, and in high temperature and outdoor work, the coating solution dries early and impairs the rusting effect. Sometimes.

(B). Similarly, high and low atmospheric humidity greatly affect rusting.

(C). When the steel surfaces to be joined are placed horizontally and in contact with an article or placed near the surface of the earth, the top surface rusts well and the bottom surface rust tends to be delayed. (It is considered that atmospheric oxygen is indispensable for the rust generation reaction, rusting is delayed on the lower surface where air circulation is poor, and rusting is promoted on the upper surface by contact with sufficient oxygen in the air.) ). Generally, the rusting phenomenon due to this type of chemical reaction has a slow reaction rate and requires several hours to ten and several hours for rusting, which causes inconvenience such as time constraint on bolting work.

<Means for Solving the Problems> The present invention is proposed in view of the above-mentioned drawbacks of the known method, and the gist thereof is to the joint surface of a steel material to be joined by a bolting method, The steel material is connected to one pole of an AC power source or an anode of a DC power source, and the counter electrode connected to the other pole of each power source is coated with a cloth-like substance made of natural or synthetic fiber Impregnated with chlorides such as iron chloride, sodium chloride, ammonium chloride and potassium chloride, nitrates such as iron nitrate, sodium nitrate, ammonium nitrate and potassium nitrate, or an aqueous solution containing one or more of hydrochloric acid, sulfuric acid or nitric acid. In the state, the counter electrode is opposed to the current-carrying treatment, and then the joining member is bolted, whereby the steel material bolt joint method is provided.

<Operation> Generally, the rusting phenomenon of metal is promoted by the activation of the surface. In the method of the present invention, a anodic dissolution action is produced by direct current electrolysis or an alternating current electrolysis method using the material to be treated as an anode, the surface is rapidly activated, and oxidation by generator oxygen generated during electrolysis is performed. Since the effect exerts an extremely effective effect on the generation of rust, a rusting phenomenon is observed immediately after the electrolytic treatment, and dense rusting is observed on the entire surface during the subsequent observation.

In the method of the present invention, the electrolytic material is not used, and the cloth-like substance coated on the counter electrode is impregnated with the electrolytic solution to form the electrolytic solution layer between the material to be processed and the counter electrode. It is possible to perform electrolysis regardless of the horizontal, vertical, or inclination, and there is no unevenness of rusting due to liquid dripping.

Further, even if oil adheres to the provisional material to be treated, the electrolytic degreasing action improves the wettability of the electrolytic solution, so that uneven rusting does not occur.

Furthermore, since the present invention is an electrochemical method, it is naturally not affected by temperature and humidity, and it is possible to generate a dense rust having good adhesion to the base material in an extremely short time (within 10 minutes at the latest). This makes it possible to perform bolting of steel materials at any time and place, at any time.

<Example> An SS41 steel plate (thickness: 19 mm; attached plate: thickness: 12 mm) whose surface was grinded to remove black skin was formed into standard test piece dimensions specified by JIS, and each joint surface was DC Was subjected to anodic electrolytic treatment. An iron nitrate aqueous solution (10% by weight) is used as the electrolytic solution, the counter electrode is made of SUS304 material, covered with a cotton cloth to impregnate the electrolytic solution, and slide on each of the joint surfaces. Then, when electricity was applied while being electrolyzed and the surface was subjected to electrolytic treatment (slowly sliding the same place several times), electrolytic degreasing action was applied to the surface, the wettability of the electrolytic solution was good, and uniform rusting was observed on the entire surface.
After tightening the standard test pieces that have undergone these rusting treatments with the high-tensile steel bolt (F10T) M20 to the prescribed torque value,
When the slip coefficient μ (friction coefficient) was calculated by applying tension with a tensile tester, 0.53 was obtained, which was a result sufficiently satisfying the specified value in the industry.

When AC electrolysis was tried instead of DC electrolysis, almost the same results were obtained. In addition to the above, chlorides such as iron chloride, sodium chloride, ammonium chloride, and potassium chloride, nitrates such as iron nitrate, sodium nitrate, ammonium nitrate, and potassium nitrate, and one or two kinds of hydrochloric acid, nitric acid, and sulfuric acid as the electrolytic solution. Almost the same results as above could be obtained with the aqueous solution containing the above.

<Effects of the Invention> In short, according to the method of the present invention, since the electrochemical method is adopted for the occurrence of rust on the steel material joint surface by the bolting method, the method is not affected by the change of season and climate, and Regardless of whether the surface of the treated material is contaminated or the orientation of the surface, it is extremely dense and evenly rusts with good adhesion to the base material, even in an extremely short time. We have succeeded in easily realizing a bolt joint surface that can obtain the friction coefficient of, and it is very useful in the construction of the friction welding method using high-strength steel bolts of steel.

Claims (1)

[Claims] 1. The steel material is connected to one pole of an AC power source or to the anode of a DC power source, and is connected to the other pole of each power source, with respect to the joint surface of the steel material to be joined by a bolting method. The counter electrode is coated with a cloth-like substance made of natural or synthetic fiber, and this coating is coated with iron chloride, sodium chloride,
The counter electrode is impregnated with a chloride such as ammonium chloride or potassium chloride, a nitrate such as iron nitrate, sodium nitrate, ammonium nitrate or potassium nitrate, or an aqueous solution containing one or more of hydrochloric acid, sulfuric acid or nitric acid. A bolt joint method for a steel material, characterized in that the joint members are bolted after being opposed to each other and subjected to an electric current treatment.