JPH0932814A - Splice plate for friction junction of high power bolt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel material for friction junction of a high power bolt having irregularities in a friction junction surface in which a high friction coefficient can be stably realized by hardening the surface. SOLUTION: A friction junction surface of a splice plate 2, in a range twice or more the diameter of a bolt 3 around the center of a bolt hole, has twice or more the roughness of a friction junction surface of counter base steel material 1, and a ten-point average roughness Rz of a roughness of 200p or more, and its hardness at 0.5mm or more from the surface in the range is twice or more the surface hardness of the counter base steel material 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a splice plate for high-strength bolt friction joining, and can be used for friction joining portions of steel structures in buildings, bridges and the like. By using the steel material of the present invention, it is possible to stably obtain a high friction coefficient of the friction-bonded surface and enhance the safety of the steel structure.

[0002]

2. Description of the Related Art In the case of high-strength bolt friction joining, according to the design and construction guidelines of the Architectural Institute of Japan, the friction surface that is important for joining strength is a good red rust surface with black scale removed and a slip coefficient of 0.
It is said that it is necessary to perform a treatment exceeding 45 and to check the slip coefficient by a slip resistance test. Normal,
It is known that in a good red rust state, the slip coefficient exceeds 0.45, and the slip resistance test is often omitted.

Although a slip coefficient of about 0.6 may be obtained in the red rust state, the rust formation state varies depending on environmental factors, steel material composition, etc., so that there are large variations, and the slip coefficient is designed to be 0.45. It seems that It is clear that the slip coefficient of the friction-bonded surface is preferably as high as possible in terms of the bonding strength. In JP-A-51-52628, the bonded surface is made uneven before construction, and in JP-A-1-206104, the bonded surface is corrosion-resistant. High frictional resistance is generated by spraying metal. However, the slip coefficient of the friction-bonded surface tends to increase as the surface roughness of the steel material increases, but there is a problem in that even if the surface roughness is increased, it does not exceed a certain value.

[0004]

DISCLOSURE OF THE INVENTION The present invention is intended for high-strength bolt friction welding which stably exhibits a high slip coefficient by having sufficient roughness and surface hardness on the friction welding surface around the bolt hole. A splice plate is provided.

[0005]

SUMMARY OF THE INVENTION The gist of the present invention is that in high-strength bolt friction welding, the area of the friction welding surface of the splice plate, which is more than twice the bolt diameter around the bolt hole, is the base steel material to be welded. The friction-bonded surface has a roughness that is at least twice the roughness, and the ten-point average roughness Rz has a roughness of 200 μm or more, and within that region, a hardness of 0.5 mm or more from the surface is the surface of the base metal material to be welded. It is a splice plate for high-strength bolt friction joining, which is more than twice the hardness.

Here, the ten-point average roughness means the surface roughness specified in JIS B0601.

[0007]

In order to increase the slip coefficient of the steel material (splice plate), it is common to increase the surface roughness of the friction joint surface by shot or grid blasting. However, the surface roughness of blast treatment is at most 150 μm in Rz, although it depends on the type of steel and shot grains.
However, there is a limit to the increase in the slip coefficient. Further, according to the research conducted by the present inventors, in order to increase the slip coefficient with the same surface roughness, it is necessary to increase the hardness (surface hardness) of the friction-bonded surface. That is,
The inventors have found that the friction-bonded surface of the splice plate is appropriately roughened with respect to the mother steel plates to be bonded and the surface hardness is increased to remarkably improve the high slip coefficient, and the present invention has been completed.

The present invention will be described below. From the viewpoint of the slip coefficient, the higher the surface hardness, the higher the roughness of the splice plate friction joint surface, and the better. First of all, how to give the roughness of the friction-bonded surface is determined by transfer (rolling) with an uneven roll such as a knurled roll, machining such as cutting, machining by laser or plasma, electrical discharge machining, or chemical such as etching. There is a target method, etc., and any method may be used. Since the roughness at this time positively increases the slip coefficient, it is an important point of the present invention that the roughness is relatively rough with respect to the surface roughness of the mother steel plates to be joined. It is considered that this is because the splice plate having a relatively coarse roughness cuts into the surface of the mother steel plate to be welded and the slip coefficient is increased by the anchor effect. The surface roughness of the joint surface must be at least twice the surface roughness of the mother steel plates to be joined. However, even if the roughness is twice or more, it is not possible to remarkably improve the slip coefficient with a roughness that can be easily applied by blasting or the like, so the absolute value of the roughness is set to Rz 200 μm or more. The larger the roughness (Rz), the higher the slip coefficient. However, when the roughness exceeds 1.0 mm, the slip coefficient is not significantly improved, and it is difficult to impart the roughness. The upper limit of Rz) is 1.0
mm. Even if the roughness is the same, the slip coefficient tends to be higher when the irregularities have regularity. For example, the pyramid shape and the mountain shape shown in FIG. 1 are the best, and the sharper the tip, the more preferable.

The area to which the above-mentioned roughness is to be imparted does not have to be the entire friction-bonding surface of the splice plate, and may be at least twice the bolt diameter centered on the bolt hole. this is,
This is because the range is limited from the range in which the axial force of the bolt at the time of bolting is applied, and even if the roughness is applied to a region of twice the bolt diameter or more, the contribution to the slip coefficient is small. However, depending on the position of the bolt hole, this is not the case when the range of twice the bolt diameter extends (extends) to the edge of the splice plate.

Next, the slip coefficient cannot be remarkably improved only by increasing the surface roughness of the friction-bonded surface as described above, and the surface hardness must be increased. This is necessary in order to maximize the anchor effect of making it penetrate into the mother steel plate to be joined, and it is necessary to have twice or more the surface hardness of the mother steel plate to be joined. On the other hand, if the hardness is less than twice, the bite will be insufficient, or the unevenness (roughness) provided will be crushed, and the effect of roughness will not be sufficiently exhibited. Here, the surface hardness means the hardness at a depth of 0.5 mm from the outermost surface in the steel plate and the plate cross section of both the mother steel plate to be joined and the splice plate, and 0.1 mm.
Vickers hardness (H
It is displayed in v). In the present invention, the splice plate including the above-mentioned portion is based on the idea that the splice plate friction-bonding surface does not sufficiently penetrate into the mother steel plate to be welded and the anchoring effect is not sufficient only by increasing the hardness of the splice plate surface. We searched for the relationship between hardness and the effect of biting into the base steel sheet to be welded and the anchor effect in all cross sections of the plate friction welded surface, and found that the hardness was found even in the area 0.5 mm or more from the outermost surface of the splice plate friction welded portion. If the surface hardness of the mother steel sheets to be joined is at least twice the surface hardness, a high biting effect and anchor effect can be achieved in combination with the above-mentioned roughness, and a high slip coefficient can be remarkably improved. Although the upper limit is not specified, it naturally has a limit depending on the composition of the steel. If the hardness is 0.5 mm or more from the surface, it is not necessary to cover the entire cross section of the steel material, and it is rather preferable that only the surface is hard in consideration of drilling of bolts.

Quenching is generally the simplest method for increasing the surface hardness, but when irregularities on the surface are to be applied by laser machining, electric discharge machining, etc. Subsequent cooling may cause quenching only on the surface, which may eliminate the need for quenching treatment. The surface roughness may be imparted in any state before and after the quenching treatment, but it is obvious that the quenching treatment is easy in the case of machining such as cutting or rolling by a knurled roll. At the time of quenching, a surface hardening treatment by carburizing and nitriding may be used together, if necessary, to effectively harden the surface.

When the surface is provided with a roughness by a rolling roll (concavo-convex processing by transfer / rolling), it may be worked cold or warm only for the purpose of providing the roughness. It is most efficient to work hot in the final rolling pass on the line, and the surface can be hardened by cooling (quenching) immediately after rolling, which is cheap and most preferable for mass production. .

In addition, by using a sufficiently high-strength steel having a required surface hardness, the requirements of the present invention can be satisfied only by providing the surface roughness without performing the surface hardening treatment.

[0014]

EXAMPLES Table 1 shows combinations of a mother steel plate to be joined and a splice plate used to illustrate the usefulness of the present invention and the resulting slip coefficient.

[0015]

[Table 1] Examples 1 to 15 are examples of the present invention, and Examples 16 to 22 are comparative examples. Table 1 shows the surface roughness (R
In addition to z) and surface hardness, the surface roughness imparting method and the surface hardening method are also described for the splice plate. The surface roughness-applied area on the splice plate side was the entire friction-bonded surface unless otherwise specified. The surface hardness in Table 1 is 0.1 mm below the outermost surface to 0.5 mm.
It is an average value of Vickers hardness measured at a load of 200 g at a pitch of 1 mm. The slip coefficient was measured using the combinations shown in Table 1 and the test pieces shown in FIG. In the measurement, the mother steel plate 1 to be joined and the jig plate 4 are made of the same steel plate (S
S400 or SM490 steel), bolt 3 was F10T, and the splice plate 2 was provided with the surface roughness and hardness according to the present invention.

Since all of Examples 1 to 15 have the surface roughness (Rz) and the surface hardness of the friction-bonded surface within the scope of the present invention, they exhibit a high slip coefficient of 0.9 or more. . The surface hardening was mainly performed by offline quenching after surface roughness was imparted, or by direct quenching after hot transfer by a roller with roughness. Although the surface roughening process was partially performed by the laser (Examples 5, 7, and 8), the required hardening depth (0.5 mm or more) can be obtained from the surface by appropriately adjusting the laser output. It shows an example that can be done. The above results show that the method does not particularly depend on the surface roughness imparting method and the surface hardening method.

On the other hand, in Comparative Examples 16 to 22, any one or more of the surface roughness (Rz), the surface hardness, and the roughness imparting area of the friction-bonded surface of the splice plate, which is a component of the present invention, is used. Is outside the scope of the present invention, so that the slip coefficient is generally low.

[0018]

According to the present invention, a stable and high slip coefficient (0.9 or more) can be easily obtained. As a result, it can be provided as a structural member that enhances the reliability of the high-strength bolt friction joint in the fields of construction and bridges, and its industrial value is great.

[Brief description of drawings]

FIG. 1 is a schematic view showing the uneven shape of a friction-bonding surface according to the present invention, in which (a) shows a pyramid shape and (b) shows a mountain shape.

FIG. 2 is a side view of a test body for measuring a slip coefficient used in the present invention.

[Explanation of symbols]

 1 ... Mother steel plate to be joined 2 ... Splice plate 3 ... Bolt 4 ... Jig plate

Claims (1)

[Claims] 1. In high-strength bolt friction welding, the area of the friction welding surface of the splice plate, which is more than twice the bolt diameter around the bolt hole, is more than twice the roughness of the friction welding surface of the base steel material to be welded. And the ten-point average roughness Rz has a roughness of 200 μm or more, and within the area, 0.5 m from the surface.
A splice plate for high-strength bolt friction welding, characterized in that the hardness of m or more is twice or more the surface hardness of the base steel material to be welded.