JPH07167129A - Set of high strength bolt, hexagon nut, and plain washer - Google Patents

Abstract

PURPOSE:To enable the hexagon nut to be used as a seat face on either surface of both surfaces in the axial direction, in a high strength bolt set. CONSTITUTION:This set is constituted of a high strength bolt, a hexagon nut 2, and a plain washer. The hexagon nut 2 is formed into a symmetrical shape provided with both faces 2a, 2b in the axial direction having equal forms to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a set of high strength bolts, hexagon nuts and plain washers.

[0002]

2. Description of the Related Art In the field assembly of a steel structure or the like, friction welding using a set of high-strength bolts, hexagon nuts and plain washers (hereinafter referred to as a set of high-strength bolts) is generally adopted. As a set of high-strength bolts, a set of high-strength bolts for friction welding, hexagon nuts, and plain washers using high-strength hexagon bolts (JIS B 1186) and structural torcia using high-strength bolts with pin tails are used. -Shaped high-strength bolt, hexagon nut, plain washer set (JSS II 0
9) is known. In both sets, the same hexagon nut and plain washer are used.

The hexagon nut has an upper surface and a lower surface,
The top surface has grades F8 and F10 depending on the mechanical properties of the nut.
Is displayed by embossing or engraving,
A seating surface having a diameter smaller than the width across flats is formed on the lower surface. Further, the flat washer is usually rounded or chamfered on the inner peripheral portion of one surface in the axial direction in order to prevent cracking due to heat treatment and interference with the bolt shaft portion. This flat washer is manufactured by punching a flat plate.

A torque coefficient value is specified for the set of high-strength bolts for friction welding, and a tightening axial force is specified for the set of structural torcia-type high-strength bolts. In order to secure these specified values, it is common practice to lubricate the hexagon nut.

The high-strength bolts, hexagon nuts, and flat washers include one flat washer or two and one hexagon nut for each high-strength bolt in order to guarantee the torque coefficient value and the tightening axial force. Shipped and used as a set with and assembled. Therefore, when using it, remove the hexagon nut and one flat washer from the high-strength bolt, insert the high-strength bolt into the bolt hole of the work to be joined, and attach the plain washer from the tip to the bolt shank protruding from the bolt hole. The hexagon nuts will be screwed together.

[0006]

When assembling a steel structure or the like, it is usual that the number of sets of high-strength bolts used is quite large. The bottom surface (the surface that is not chamfered or rounded on the inner circumference) contacts the work piece, and the bearing surface of the hexagon nut contacts the flat washer. Generally difficult. In particular, when the assembly work is performed in a dark place where the illumination is not sufficient, the hexagon nut and the flat washer are apt to be used with the upper surface and the lower surface in the wrong state. If the high-strength bolt is tightened with such an error occurring, the tightening axial force becomes unstable.

Further, when the flat washer is manufactured by punching from a flat plate, the flat washer is bent, but it is difficult to correct the bend so that the upper and lower surfaces are symmetrical planes. . For this reason, the upper and lower surfaces of the flat washer may hit against the hexagon nut or the workpiece, which may cause a problem such as rotation of the flat washer during tightening.

[0008]

In order to eliminate the mistake of using the above-mentioned set of high-strength bolts, the present inventor has the same shape for the hexagon nut and the flat washer even if the upper surface and the lower surface thereof are reversed. It is formed as follows.

That is, the invention according to claim 1 for solving the above-mentioned problems is a set of a high-strength bolt, a hexagon nut, and a flat washer, which comprises a high-strength bolt, a hexagon nut, and a plain washer.
Both sides of the hexagonal nut in the axial direction are symmetrically formed with bearing surfaces having the same shape.

The symmetry in this case means that both sides of the hexagonal nut are rotationally symmetric with respect to each other by 180 degrees with a line orthogonal to the axis of the hexagonal nut and passing through the center of the nut as the axis of symmetry. Mean (hereinafter the same).

According to a second aspect of the present invention for solving the above-mentioned problems, in the set of the high-strength bolt, the hexagon nut, and the flat washer according to the first aspect of the present invention, the bearing surfaces on both axial sides of the hexagon nut are provided. In addition, a marking that indicates the grade of mechanical properties is displayed by engraving, and a lubricating film is formed.

According to a third aspect of the invention for solving the above-mentioned problems, in the set of the high-strength bolt, the hexagon nut, and the plain washer according to the first or second aspect of the invention, the bearing surface of the hexagon nut is It is characterized in that the central part in the radial direction is formed into a convex curved surface projecting in the axial direction over the entire circumference.

The invention according to claim 4 for solving the above-mentioned problems is a set of a high-strength bolt, a hexagon nut, and a plain washer according to any one of the inventions of claims 1 to 3.
The flat washer is characterized in that both sides in the axial direction are symmetrically formed by chamfering or rounding the inner peripheral portions by cold forging by a former.

[0014]

In the invention according to claim 1, since both sides of the hexagonal nut are formed symmetrically with the seating surfaces of the same shape, one of the two sides of the hexagonal nut contacts the flat washer. Even if it is used as described above, there is no difference in the stability of the tightening axial force.

In the invention according to claim 2, since the groove of the display symbol portion indicating the grade of the mechanical property displayed by the marking on the bearing surface of the hexagon nut serves as a lubrication pool,
Lubricity can be improved, co-rotation of the flat washers can be prevented, and the tightening axial force can be made stable.

In the invention according to claim 3, since the bearing surface of the hexagonal nut is formed into a convex curved surface, it is more advantageous for stabilizing the tightening axial force than when the bearing surface is formed flat. . That is, when the seat surface of the hexagonal nut is formed flat, one-sided contact with the washer is likely to occur, and the tightening pressure tends to be uneven. However, in the case of the invention according to claim 3, the hexagonal nut is Since the seat surface is formed in a convex curved surface, it is easy to contact the flat washer uniformly over the entire circumference, and the tightening axial force can be stabilized.

In the invention according to claim 4, the flat washers are chamfered or rounded on both inner surfaces, so that the flat washers are used so that either the upper or lower surface comes into contact with the work. Also, since the flat washer is formed by cold forging with a former, there is no bending unlike in the case of punching, its correction is unnecessary, and the problem of one-sided contact is eliminated.

[0018]

Therefore, according to the first aspect of the invention, in a set of a high-strength bolt, a hexagon nut, and a flat washer, both sides in the axial direction of the hexagon nut are provided with bearing surfaces of the same shape. Since the hexagonal nut is formed into a shape, any of its two surfaces may contact the flat washer, and the upper surface and the lower surface (seat surface) are erroneous even when used in the dark. The problem is solved and a stable tightening axial force can always be obtained.

According to the invention of claim 2, in the set of the high-strength bolt, the hexagon nut, and the flat washer, an indication indicating the grade of mechanical properties is provided on each bearing surface on both sides in the axial direction of the hexagon nut. Since the symbol is displayed by engraving and a lubricating film is formed, the groove in the symbol indicating the grade of this mechanical property serves as a lubrication reservoir, which is advantageous in stabilizing the tightening axial force. become.

According to the invention of claim 3, in the set of the high-strength bolt, the hexagonal nut, and the flat washer, since the bearing surface of the hexagonal nut is formed into a convex curved surface, the hexagonal nut and the plain washer are Is uniform over the entire circumference, which is advantageous in stabilizing the tightening axial force.

According to the invention of claim 4, in the set of the high-strength bolt, the hexagonal nut, and the flat washer, the flat washer is formed by cold forging by a former, and both sides in an axial direction are mutually inward. Since the peripheral washer is formed in a symmetrical shape with a chamfer or a rounded shape, the flat washer may have any of the upper and lower surfaces in contact with the work, and there is no bending as in the case of punching. The correction is unnecessary, and the problem of one-sided contact is eliminated, which is advantageous in stabilizing the tightening axial force.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

<Structure> FIG. 1 shows a state in which two steel works W1 and W2 are tightened using a set of structural torcia type high strength bolts, hexagon nuts and plain washers. In this set, 1 is a high-strength bolt, 2 is a hexagon nut, 3
Is a flat washer. A pin tail 1c is projectingly provided at the tip of the threaded portion 1a of the high-strength bolt 1 through a fracture groove 1b.

The hexagonal nut 2 is formed symmetrically on both sides in the axial direction with bearing surfaces of the same shape. That is, as shown in FIG. 2, an annular bearing surface 2a having a diameter smaller than the width of two flat surfaces and protruding in the axial direction is formed on one end surface in the axial direction of the hexagonal nut 2, and the other end surface in the axial direction is also formed in FIG. Similarly, an annular seat surface 2b having a diameter smaller than the width across flats and protruding in the axial direction is formed. Both seating surfaces 2a, 2b
Are marked with markings 2c and 2d indicating the grade F10 according to the mechanical properties of the nut. Further, as shown in FIG. 4, the two bearing surfaces 2a, 2b are formed as curved surfaces in which the central portion in the radial direction projects in the axial direction over the entire circumference.

The flat washer 3 is formed by cold forging with a former, and as shown in FIGS. 5 and 6, chamfers 3 are formed on the inner peripheral portions of both axial surfaces thereof.
a and 3b are formed, and both surfaces are symmetrical to each other.

A lubricating film is formed on the surface of the hexagon nut 2 by surface treatment.

<Effects> Therefore, since the hexagon nut 2 of the set of high-strength bolts is symmetrically formed on both surfaces, whichever surface is used for contacting the flat washer 3, There is no difference in tightening axial force. Moreover,
Marking symbol 2 is provided on both bearing surfaces 2a and 2b of the hexagon nut 2.
Since c and 2d are displayed by engraving, the grooves of the symbols 2c and 2d generated by this engraving serve as a lubrication pool, and the lubricity between the hexagon nut 2 and the flat washer 3 at the time of tightening is good. The tightening axial force can be stabilized.

Further, since both sides of the plain washer 3 are formed symmetrically, there is no difference in the tightening axial force even if either side is used in contact with the work.

Further, when the bearing surface of the hexagonal nut is formed flat, one-sided contact with the washer is likely to occur, and the surface pressure tends to become uneven. Since the seat surfaces 2a and 2b are formed into convex curved surfaces, it is easy to contact the flat washer 3 uniformly over the entire circumference, which is more advantageous in stabilizing the tightening axial force.

-Comparative Test-A test was conducted on the relationship between the seat surface shape of the hexagon nut and the tightening axial force. That is, a hexagonal nut (conventional example) whose seat surface is flat and does not have the above-mentioned symbol, a hexagonal nut whose seat surface is convexly curved and does not have the above-mentioned symbol, and whose seating surface is convexly curved. And prepare 3 types of hexagon nuts, each of which is engraved with the above display symbol, 10 pieces each,
The tightening axial force of each was measured. The test conditions are as follows.

(Test conditions) (1) Convex curved surface of the seat surface; r = 15 mm (2) Indication symbol; FIG. 7 shows the plan shape. Length L = 5mm, Width W = 0.5mm, Depth = 0.3mm (3) Test bolt; Torcia type high strength bolt M20 × 60 (4) Test temperature; 25 ℃ The results are shown in Table 1. There is.

[0032]

[Table 1]

According to Table 1 above, the standard deviation σ and variation coefficient cv of the tightening axial force of the above-mentioned three types of hexagonal nuts are smaller for the convex curved surface than for the flat bearing surface, and The convex curved surface engraved with the display symbol is even smaller. From this, it is effective to make the seating surface a convex curved surface in order to reduce the variation in the tightening axial force, and to engrave a display symbol on the seating surface also reduces the variation in the tightening axial force. It turns out to be effective above.

Further, since the flat washer 3 is formed by cold forging by a former, it does not cause the problem of bending and one-sided contact that accompanies the case of punching, which also causes the above-mentioned tightening shaft. It is advantageous for stabilizing power.

That is, FIG. 8 is obtained by scanning the surface 3c of a flat washer formed by cold forging by a former in a diametrical direction with a contour measuring instrument, and FIG. 9 is a view of a flat washer formed by punching. It is obtained by similarly scanning the surface 3c '. As is clear from a comparison between these two figures, the punched one has a large peripheral sag, which tends to cause one-sided contact, whereas the cold forging by a former has high flatness on both sides. It can be seen that it is possible to prevent uneven contact.

FIG. 10 shows another embodiment of the flat washer. The flat washer 4 is formed in a symmetrical shape with both sides having rounded portions 4a and 4b on the inner peripheral portions thereof. .

FIG. 11 shows an example in which the present invention is applied to a high-strength hexagon bolt. That is, in FIG.
1 is a hexagon bolt, 12 is a hexagon nut, and 13 is a flat washer. In the set, the plain washer 12 is a hexagon bolt 11
2 sheets are provided, one on each side and the hexagon nut 12 side. The hexagonal nut 12 has a bearing surface 12a having the same shape as the torcia-shaped one described above on both sides in the axial direction,
12b is formed symmetrically, and the flat washer 13 is also formed in the same shape as that of the torcia type. Therefore, also in the case of this example, the same operational effect as in the case of the torcia type can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a usage state of a set of torcia type high strength bolts.

FIG. 2 is a view showing one surface in the axial direction of the hexagon nut of the set.

FIG. 3 is a view showing the other surface in the axial direction of the hexagon nut of the set.

FIG. 4 is a side view showing the hexagon nut of the above set in a partial cross section.

FIG. 5 is a plan view showing a flat washer of the above set.

FIG. 6 is a side view showing the flat washer of the set in a partial cross section.

FIG. 7 is a plan view showing display symbols indicating grades of nuts according to mechanical properties.

FIG. 8 is a diagram obtained by scanning the surface of a flat washer formed by cold forging by a former in a diametrical direction with a contour measuring instrument.

FIG. 9 is a diagram obtained by scanning the surface of a plain washer formed by punching in a diametrical direction with a contour measuring instrument.

FIG. 10 is a side view showing another example of the flat washer with a partial cross section.

FIG. 11 is a cross-sectional view showing a use state of a set of high-strength hexagon bolts for friction welding.

[Explanation of symbols]

 1,11 High-strength bolt 2,12 Hexagon nut 2a, 2b Seat surface 2c, 2d Indication symbol 3,4,13 Flat washer 3a, 3b Chamfer 4a, 4b Roundness

Claims (4)

[Claims] 1. A set of a high-strength bolt, a hexagon nut, and a flat washer comprising a high-strength bolt, a hexagon nut, and a flat washer, wherein both sides in the axial direction of the hexagon nut have seating surfaces of the same shape. A set of high-strength bolts, hexagon nuts, and plain washers, which are characterized by being formed symmetrically. 2. The set of high-strength bolts, hexagon nuts, and plain washers according to claim 1, wherein each bearing surface on both axial surfaces of the hexagon nut is engraved with a marking indicating the grade of mechanical properties. A set of high-strength bolts, hexagon nuts, and plain washers that are displayed and have a lubricating film formed. 3. The set of high-strength bolts, hexagon nuts, and flat washers according to claim 1 or 2, wherein the seat surface of the hexagon nut has a central portion in the radial direction that projects in the axial direction over the entire circumference. A set of high-strength bolts, hexagon nuts, and flat washers characterized by being formed into a convex curved surface. 4. The set of high-strength bolts, hexagon nuts, and flat washers according to claim 1, wherein the flat washers are formed on both sides in the axial direction by cold forging with a former. Structural bolt characterized by being formed symmetrically with chamfered or rounded inner circumference
A set of hexagon nuts and flat washers.