JPS6366907B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a friction bonded body for steel structures, and more specifically, mill scale (mill scale) that always occurs incidentally on the steel surface when the steel material is roll rolled. This invention relates to a friction bonded body that uses black peel to improve the friction bonding surface of steel materials.

[Conventional technology]

It is well known that when building structures by joining steel materials together, a friction welding method is used in which frictional force is applied to the joint surfaces to strengthen the joint.

By the way, when steel materials are produced by roll rolling,
Mill scale always occurs on the steel surface. Although this is strong, it has the disadvantage that if it remains, it becomes a slippery joint surface. Therefore, mill scale has traditionally been treated as useless and as something that must be removed in order to make the joint surfaces less slippery. As a result, the mill scale is removed using a grinder or the like, and then red rust is generated, so that the parts are joined on this red rust surface.

[Problem to be solved by the invention]

Once the mill scale is removed from the steel surface as described above, the base metal will be exposed, and rust will progress after the steel frame is shipped from the factory. Therefore, if floating rust occurs, it must be removed at the construction site, which requires wire brushing.
There are problems that require time and effort.

The present invention was made in view of the above problems, and its purpose is to eliminate the trouble of removing mill scale with a grinder or the like or removing floating rust with a wire brush, and conversely utilize the advantages of mill scale. It is an object of the present invention to provide a friction bonded body of a steel structure whose bonding surface can be finished to a desired roughness by chemical treatment without machining.

[Means to solve the problem]

The feature of the friction bonded steel structure of the present invention is that the smooth mill scale surface of the steel material is chemically treated with a treatment agent containing dilute hydrochloric acid, a surfactant, and a hydrogen embrittlement inhibitor. By finishing the surface to a roughness of ~50s, the coefficient of friction was increased to above the standard value.

[Effect]

Mill scale occurs on the surface of steel products when they are produced, but without removing it, the smooth steel surfaces that will be friction-bonded into steel structures can be treated with treatment agents containing dilute hydrochloric acid, surfactants, and hydrogen embrittlement inhibitors. chemically treated. Because mill scale exists,
Due to its rust resistance, the joint surface has a
Finished with a rough surface of about 50s. Therefore, the coefficient of friction at that location can be set to sufficiently meet the standard value set by the Architectural Institute of Japan.

〔Effect of the invention〕

According to the present invention, it is possible to eliminate the trouble of removing mill scale, which must be removed without fail, and improve workability. On the contrary, the rust-inhibiting effect of mill scale can be exerted, and the friction coefficient of the joint surface can be brought to a desired value much more easily than before. Furthermore, the sliding strength does not decrease due to mill scale remaining after the surface is roughened after chemical treatment, and the change in sliding strength over time is extremely small.

〔Example〕

When making a structure by joining steel materials together, a friction joining method is used in which frictional force is applied to the joint surfaces to strengthen the joint. On the other hand, when a steel material is produced by roll rolling, mill scale is always generated on the surface of the steel material. Although this is solid, if it remains, it becomes a slippery joint surface, but it itself has a rust inhibiting effect. Focusing on this, it was found that the friction coefficient at the joint surface could achieve the standard value specified by the Architectural Institute of Japan.

By the way, in Japanese Patent Application Laid-open No. 195245/1982 (Japanese Patent Application No. 52932/1982), the present applicant has disclosed a technique in which a nonwoven fabric or the like is impregnated with a substrate conditioning liquid as a mill scale removal liquid and is adhered for a certain period of time. Therefore, we proposed chemical treatment of the joint surfaces of steel materials. In the present invention, a chemical treatment agent in the form of a mixed solution containing, for example, the following agents is used as the substrate conditioning liquid. These include dilute hydrochloric acid, thickeners, surfactants, etching inhibitors, and hydrogen embrittlement inhibitors. In particular, it is effective to contain dilute hydrochloric acid, a surfactant, a hydrogen embrittlement inhibitor, and the like.

That is, the nonwoven fabric is effective in preventing evaporation of the chemical solution, and is removed after a certain period of time. When the loose mill scale is removed with a wet rag, the hydrochloric acid in the chemical solution reacts with the mill scale and the steel, leaving a small amount of ferric chloride and moisture on the steel surface. Ferric chloride is the main component of the rust starter, and since red rust occurs rapidly thereafter, the very desired surface roughness described above can be obtained.

In this way, if there is mill scale on the steel surfaces to be joined, the chemical treatment agent will roughen the surface for about 25 to 50 seconds, and the friction coefficient will be a stable value of 0.55 to 0.60. This is the standard value of Architectural Institute of Japan 0.45
This fully satisfies the following. In addition, the above s is a display value stipulated in "Definition and Display of Surface Roughness" of B0601 of the Japanese Industrial Standard (JIS), and is related to the maximum height (Rmax) of surface roughness. be. It is based on the "standard number sequence of maximum height" used when specifying surface roughness by maximum height, and specifies surface roughness by the maximum allowable value of maximum height. If the above
This is the symbol added after the numerical value selected from the numerical sequence in Table 4 described in 3.4.2 of JIS-B0601.

By the way, according to the results of experiments conducted by the present inventors, it was found that the surface was significantly different from the untreated mill scale surface. That is, it was also confirmed that mill scale remaining after the surface is roughened after chemical treatment does not necessarily lead to a decrease in sliding strength. Comparing the surface from which mill scale has been removed by a grinder and the chemically treated surface of the present invention, in the case of the present invention, due to the rust resistance of the mill scale, rust, which is a defect such as a finished surface with exposed bare skin, occurs as in the conventional method. ease of occurrence,
It can be said to be extremely superior as it is soft and does not cause flaking or floating rust.

As a result of the experiment, regarding the chemically treated friction surface,
The following conclusions were obtained.

(a) Mill scale that remains after the surface is roughened after chemical treatment does not cause a decrease in sliding strength.

(b) Changes in sliding strength over time are extremely small.

(c) Bolt relaxation is equivalent to that of sanding.

In this way, the present invention eliminates the hassle of removing mill scale and the wire brushing work at the construction site to remove floating rust after removing mill scale, which was considered to be necessary in the past. By utilizing the effects of mill scale, it is possible to remove mill scale and generate red rust at the same time, making it easier to improve the coefficient of friction at joint surfaces than before.

Claims (1)

[Claims] 1 The smooth mill scale surface of the steel material is chemically treated with a treatment agent containing dilute hydrochloric acid, a surfactant, and a hydrogen embrittlement inhibitor to make the surface rough for about 25 to 50 seconds, thereby reducing the coefficient of friction to the standard value. A friction bonded body of a steel structure characterized by the above.