JPS6220736Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a high-strength bolted joint structure.

According to Japan's current design standards for high-strength bolted joints, the allowable design stress is determined not to exceed the sliding load between the base materials. However, there is a relationship between the load and the amount of slip as shown schematically by the solid line in FIG. 1, and even if main slip occurs, there is still considerable margin in the strength of the high-strength bolt itself.

Therefore, in order to make efficient use of the strength of high-strength bolts, it is necessary to improve the allowable proof stress compared to the current standards. For this purpose, as shown by the dashed line in Figure 1, there is a method of increasing the frictional resistance between the base materials to greatly increase the sliding load, and a method of increasing the sliding load between the base materials by increasing the stress as shown by the broken line in Figure 1. There is a method in which the bearing pressure effect prevents main slip from occurring even if the load exceeds the load.

This idea focuses on the latter of the above two methods, and uses a special washer to fill the clearance between the bolt and the bolt hole, and the resulting bearing pressure effect between the bolt shaft and the base material increases the allowable proof stress. A significant increase can be expected. The details will be explained below with reference to the drawings.

FIGS. 2 and 3 show an embodiment of this invention.

Bolt holes 3 and 4 are provided in corresponding positions in the polymerized base materials 1 and 2, respectively. The base materials 1 and 2 are joined by a bolt 5 passing through the bolt holes 3 and 4 and a nut 6 screwed into the bolt 5. Head 5a of this bolt 5
Washers 7 are interposed between the nut 6 and the base material 1 and between the nut 6 and the base material 2, respectively.

The washer 7 is formed into a substantially flat annular shape as shown in FIGS. 2a and 2b, and on the inner circumference of the surface on the base material 1 or 2 side, arcuate centers are formed into chevrons at 3 to 4 equally spaced locations. A protruding strip 7a having a swollen cross-sectional shape is provided, and the chevron-shaped top portion of the protruding strip 7a is formed near the bolt insertion hole of the washer 7.

In such a configuration, when the nut 6 is tightened, the protrusion 7 of the washer 7 will be removed as shown in FIG. 3b.
a bites into the surfaces of the base materials 1 and 2 near the bolt holes 3 and 4, and the base materials 1 and 2 are pushed out toward the bolt holes 3 and 4.

The extruded base materials 1 and 2 fill the clearance between the bolt holes 3 and 4 and the bolt shaft 5b. As a result, even after the stress exceeds the slip resistance of the friction surface, the resistance increases due to the bearing pressure without causing a large slip phenomenon.

With this invention, when the bolts and nuts are tightened, the base metal is deformed by the washer to fill the clearance between the bolt shaft and the bolt hole, so conventional bolts and nuts can be used as they are.

The clearance between the bolt hole diameter and the bolt shaft diameter may be 1.0 to 1.5 mm, as in the conventional case, and does not require particularly high machining accuracy.

Although it is particularly effective for joining in one-plane shear, it can also be used for two-plane shear to reduce the amount of slippage.

The on-site tightening work of high-strength bolts is exactly the same as conventional bolts, and construction is simple.

You can expect similar effects.

Moreover, this invention can increase the allowable proof stress of each high-strength bolt, and the strength of the high-strength bolt itself can be utilized without wasting it. Since the number of bolts at the joint can be reduced, it is possible to improve work efficiency and reduce costs on site.

[Brief explanation of the drawing]

Figure 1 is a load-displacement curve diagram, Figure 2 a is a front view of the washer, b is its A-A sectional view, Figure 3 a,
b is a cross-sectional view. 1, 2... Base material, 3, 4... Bolt hole, 5...
Bolt, 5a...Head, 5b...Bolt shaft, 6...
...Natsuto, 7...Washiya, 7a...Protrusion part.

Claims (1)

[Scope of utility model registration request] In a high-strength bolt joint structure in which a bolt hole is provided in a polymerized base material and the bolt is joined by a bolt passing through the bolt hole, a washer formed in a substantially flat annular shape is attached to the base material for the bolt and nut. The washer is provided with a plurality of protrusions arranged at equal intervals on the inner periphery of the surface of the base material to be joined, each having a cross-sectional shape in which the center of a plurality of circular arcs swells into a chevron shape, The chevron-shaped top portion of this protrusion is formed near the bolt insertion hole of the washer, and the clearance between the bolt hole in the base material and the bolt shaft is filled by extrusion deformation of the base material due to tightening of the bolt and nut. High-strength bolted joint structure.