JPH09276970A - Friction joining part of high strength bolt without using patching plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the high slip factor and the high joining proof stress by forming sharp pyramid or conical type roll-forming pattern at the tip part around a bolt hole on either one side of faced friction joining surfaces at the friction joining part of the high strength bolt without using a patching plate. SOLUTION: Hardness at projecting parts with the roll-forming is risen by work hardening to obtain the higher slip factor than the machining method in the same projecting and recessing shape. At the time of roll-forming, a method by using a knurling tool is the simplest. In the case of applying to the joining part without using the patching plate between a gusset plate and a small beam or a brace as members constituting a steel structure, a method for roll-forming around the bolt hole on the flat plate-like joining part by fitting to a drilling machine regardless of a portable type or the one with NC device, is the most desirable. Further, the pyramid type roll-forming pattern is easily obtd. by using the knurling tool combining a nick pattern having some angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel material for high-strength bolt friction joining, and is used for a friction joining portion of a steel structure in a building, a bridge or the like.

[0002]

2. Description of the Related Art In friction welding of high-strength bolts, according to the design and construction guidelines of the Japan Institute of Architecture, the friction surface that is important in terms of welding strength is a good red rust surface with black skin removed and a slip coefficient of 0.45. It is said that it is necessary to confirm the slip coefficient with a slip proof test after applying a higher treatment. 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 higher the slip coefficient of the friction-bonded surface is, the better in terms of bonding strength.
In JP-A No. 28-28, the joint surface is made uneven before construction, and in JP-A-1-206104, a corrosion-resistant metal is sprayed on the joint surface to generate a high frictional resistance, but in terms of processing efficiency and cost. There was a problem. In addition, these high friction treatments are usually performed on the splicing plate, and for the joints such as gusset plate, which is a member constituting the steel structure, and the beam and braces, which do not use the splicing plate. There was a problem that it was not done.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high strength bolt friction joint which stably exhibits a high slip coefficient.

[0006]

SUMMARY OF THE INVENTION The gist of the present invention is that in high-strength bolt friction joining without using a splicing plate, a sharp tip is provided around one of the bolt holes on the friction joining surface of the facing steel material. A high-strength bolt friction joint without using a splicing plate, having a pyramidal or conical rolling pattern.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In order to increase the slip coefficient of a steel material, a method of increasing the surface roughness of a friction-bonded surface by shot or grid blasting is adopted. However, in the blast treatment and the like, the surface roughness, that is, the height difference of the surface irregularities is about 150 μm at the most, depending on the steel type, shot grains, etc., and there is a limit to the increase in the slip coefficient due to this.

As a method for imparting a relatively large roughness exceeding 150 μm to the surface of the friction-bonded surface, a mechanical cutting method,
Various methods such as laser and plasma processing are conceivable, but the inventors of the present invention can easily apply them to joints that do not use a splicing plate such as gusset plates, which are members that make up a steel structure, and small beams and braces. As a result of diligent examination of the method of obtaining, it was found that rolling is most preferable.

The hardness of the convex portion formed by rolling increases due to work hardening, and the same uneven shape (uneven height, sharpness of tip, etc.)
If so, the slip coefficient is higher than that of the mechanical cutting method. It is presumed that this is because the harder the convex portion, the greater the bite into the opposing steel material surface.

When rolling, a method using a commercially available knurling piece is the simplest. Normally, a knurled piece is mounted on a lathe and is rolled, but a joining portion such as a gusset plate, a beam or a brace, which is a member constituting a steel structure targeted by the present invention, without using a splicing plate. For the purpose of carrying out the present invention, the method of attaching to a drilling machine regardless of whether it is portable or having an NC device and rolling around the bolt hole of the flat plate-like joint is the most preferable for carrying out the present invention. FIG.
In order to obtain a pyramidal rolled pattern as shown in (3), it is easy to obtain by using a combination of knurled patterns with a certain angle.

The rolling pattern by the drilling machine and the knurling piece is inevitably imparted concentrically around the bolt hole, and it should be taken into consideration that the axial force distribution at the time of bolt fastening decreases monotonically as the distance from the bolt hole increases. Therefore, it is extremely efficient in practice. According to the experiments conducted by the inventors, the area of application of the concavo-convex rolled pattern depends on the concavo-convex shape, but the area of a circle centered on the bolt hole and having a radius of about 1.5 to 4 times the radius of the bolt hole is the most. Although preferable, it is not always necessary to cover the entire surface within the area.

Although the height of the unevenness is not specified,
Roughness that can be easily imparted by shot blasting, etc., that is, 150 μm or more is preferable, and the upper limit is also limited by the knurling piece, but even if it exceeds 2 mm, the slip coefficient does not significantly increase, and it is effectively 2 mm or less. is there.

It is needless to say that the sharper the tip of the unevenness, the easier it is to bite into the opposing steel material. Also, the reason why the shape is limited to a pyramid or a cone is that, for example, when joining braces, the force acting on the joint has not only a simple tensile component but also a shearing component, so that it is effective in all directions. And FIG. 2 shows an example of a pyramidal concavo-convex pattern.

By using a drilling machine for imparting a rolling pattern, it is possible to perform rolling simultaneously with the processing of bolt holes, and work efficiency can be dramatically improved. In addition, since a portable drilling machine is also available, it is possible to carry out local processing.

Further, generally, since it is necessary to generate red rust at the joint portion, masking at the time of coating or removal of the coating is required. However, in the present invention, a sufficiently large roughness can be imparted, and therefore, from the viewpoint of coating. It is possible to join without rolling or reversely removing the coating on the opposite steel material side. These rolling patterns do not have to be on both of the friction-bonding surfaces that face each other, and only one of them needs to be formed.

[0016]

EXAMPLES Table 1 shows rolling patterns (shapes) of friction-bonded surfaces used for illustrating the usefulness of the present invention and slip coefficients measured using a test body as shown in FIG. Is.
In each of the comparative materials, a concavo-convex pattern was provided on the friction-bonded surface by the mechanical cutting method.

In the method of using the drilling machine and the knurling piece according to the present invention, the surface area provided with the concavo-convex pattern is compared with the entire area within a circle having a radius of 3 times (36 mm) the radius of the bolt hole (12 mm) around the bolt hole. In the method by mechanical cutting in the example,
A 72 mm × 72 mm area (a square area in which a circle having a radius of 36 mm, which corresponds to the processing area in the present invention, is circumscribed) was formed around the bolt hole. The steel materials 1 and 2 to be bolt-bonded were both SM490 having a plate thickness of 12 mm, and only the steel material 2 to be bonded was processed to have an unevenness around the bolt holes. Also, the bolt 3 is F10T-
M22 was used.

[0018]

[Table 1]

The method (symbols A and B) according to the present invention has a slip coefficient equal to or higher than that of the machine cutting method in the comparative example as long as the concavo-convex shapes are the same, and the ease of pattern application and the processing efficiency are improved. Considering this, it is an extremely excellent method. Further, it is clear that it has a very stable and high slip coefficient as compared with the red rust state and the shot blast treatment.

[0020]

EFFECTS OF THE INVENTION According to the present invention, the slip coefficient of a high-strength bolt friction joint portion which does not use a splicing plate can be stably increased, and the joint strength per bolt can be increased. As a result, in the fields of construction and bridges, it is possible to reduce the number of bolt fastenings and shorten the construction period.In addition, if the number of bolt fastenings is the same, the reliability and safety of the friction joint will be further enhanced, and its industrial value will be great. Is.

[Brief description of drawings]

FIG. 1 is a plan view and a side view showing a test body for measuring a slip coefficient.

FIG. 2 is a schematic view showing a pyramid-shaped rolling pattern on the friction-bonding surface of the present invention.

[Explanation of symbols]

 1 Bonded steel 2 Bonded steel with rolling pattern 3 High-strength bolt

Claims (1)

[Claims] 1. In high-strength bolt friction welding without using a splice plate, a pyramidal or conical rolling pattern with a sharp tip is provided around one of the bolt holes on the friction welding surface of the opposing steel material. A high-strength bolt friction joint without using a splicing plate.