JPS6059446B2 - Constant torque breaking nut with display cover - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a constant torque break nut, and more particularly to a nut having a break indicator function.

Constant torque breaking nuts, which break at a constant torque, are often used in parts where reliable tightening is important, such as connecting parts of architectural structures and electrical conductor connections.

There are two types of constant torque breaking nuts: those of a type in which a portion of the nut falls off after tightening and breaking, and those of a non-falling type that retains a loosening function as a double nut after breaking.

The former clearly indicates the breakage, but after the breakage, the tightening condition is no different from that of a general single nut, and even if you take the trouble to tighten it to a constant torque, it has the disadvantage that it cannot guarantee that it will not become loose afterward. There is.

On the other hand, the latter has a so-called double-nut loosening function, since the nut is double-tightened even after the nut breaks after constant torque tightening, and is far superior to the former in terms of long-term fastening guarantee.

To explain this with drawings, FIG. 1 shows the tightened state of the double nut type constant torque nut before breaking, and FIG. 2 shows the state of the nut after breaking.

After the upper nut lb is broken, it rotates at an arbitrary angle, and as shown in the top view A of FIG. 2, the breakage is recognized by the angle deviation from the lower nut 1a. However, the amount of rotation of nut lb is not constant, and when rotated by a multiple of 600, it overlaps with nut 1a,
It may be difficult to distinguish the difference. In order to solve this problem, it is necessary to devise a way to recognize the original position using, for example, a color display 8. In order to be able to identify this display from any direction, it is usually necessary to display it on three sides, and for the same reason as above, it is necessary to use truly cumbersome methods such as dividing the color into three colors. The reality is that you can't get it.

In addition, when used at high places, such as in the fastening parts of architectural components, it is necessary to identify numerous broken nuts from 7 separate positions, but the method based on color fading cannot be used to accurately determine the number of broken nuts. It is difficult unless you get close to about 2TrL,
It had become a big obstacle.

Furthermore, even if the nut has been tightened with a constant torque, it is difficult to identify this if the nut is subsequently rotated artificially for some reason, so a mechanism that can prevent this is also desired. The purpose of the present invention is to eliminate the drawbacks of the prior art described above, provide a clear indication of breakage, and provide a
An object of the present invention is to provide a new constant-torque breaking nut that does not have to worry about being loosened artificially.

That is, the gist of the present invention is to provide an indicator cover that is attached to an auxiliary nut (upper nut) that separates at the same time as a constant torque fracture so that it can be engaged with a wrench, and a protective cover that prevents artificial loosening of the main nut (lower nut). The reason is that it is integrated and installed.

An example of this will be explained below with reference to FIG.

The cover 3 is molded in one piece from synthetic resin or the like.
The lower cover 3a is fitted with the lower nut 1a with as little clearance as possible, and has a protrusion that fits into the groove 2 of the nut at a portion to prevent vertical movement. The cover is press-fitted into the nut using its elasticity.

A gap 5 is provided between the upper cover 3b and the upper nut 1b, and a hexagonal box wrench 4 for tightening and rotating the upper nut can be fitted into this gap. A groove 6 is provided at the boundary between the upper cover and the lower cover.

Now, to explain this action, when the upper nut is tightened with the wrench 4, the nut cover rotates as a unit, and when a constant torque is reached, the lower nut and lower cover stop rotating, and then the notch ．． The upper nut broken in groove 2 is rotated by an arbitrary amount.

At this time, the inner surface of the upper cover is fitted with the outer surface of the wrench, so they try to rotate together, but the lower cover, which is formed as one piece, is fitted in a non-rotatable state with the lower nut, which has already stopped rotating. power because it is One bar is shear fractured in the groove 6, so the top cover 3b is separated and a constant torque fracture is indicated. FIG. 4 shows the appearance before breaking, and FIG. 5 shows the appearance after breaking. The conspicuousness of the display can be clearly understood.
In Fig. 3, the upper cover is fitted to the outer surface of the wrench, but the point is that the upper cover only needs to be able to rotate together with the wrench during constant torque rupture, for example by protruding a pin-shaped protrusion from the wrench. Of course, it may be connected to the upper cover. Further, the shape of the groove 6 is not limited to the shape shown in the figure, as long as it can be formed into a small cross section that facilitates shearing.

Furthermore, such a shear-enhancing portion can be set by an adhesive portion in which upper cover 3b and lower cover 3a, which have been separated and molded in advance, are adhered and integrated.

According to the present invention, constant torque fracture can be more clearly displayed than separation and falling off of the lower cover caused by rotation of the upper cover provided on the wrench-engaging nut side by the wrench, and especially compared to conventional This makes identification from a distance, which used to be difficult, extremely easy, and its effects are remarkable.

Further, by distinguishing the upper cover and the lower cover by color, more effective identification is possible. Another novel advantage of the present invention is that the lower cover remains as a protective cover. That is, as mentioned above, with the conventional constant torque breaking nut, even if the lower nut, which is the main nut, was turned artificially for some reason, it could not be identified, and there remained concerns regarding practical use. However, in this display cover, the lower cover is left in a form that completely surrounds the main nut, so the only way to rotate the main nut is to destroy the lower cover, in other words, the lower cover is left behind. Constant torque tightening is guaranteed as long as the

As a result, the drawbacks of the prior art are completely eliminated, and an ideal constant torque nut that is excellent in display effects, anti-loosening effects, and elimination of artificial disturbances can be realized.

Furthermore, it is possible to provide an economical display method with superior productivity compared to conventional techniques. Further, in the constant torque breaking nut of the present invention, the upper cover, which is separated and removed from the lower cover fixed onto the nut and the lower nut, has a gap between which a wrench can be inserted between the upper cover and the upper nut it covers. Since the wrench is engaged with the wrench and separated from the lower cover, constant torque rupture of the nut and separation of the abutting upper cover are performed while the wrench is directly engaged with the upper nut. Therefore, by providing the display cover over the nut, problems such as incomplete engagement of the wrench with the nut, which are likely to occur, can be eliminated, and accurate constant torque tightening and correct tightening history display can be ensured. It is highly reliable.

[Brief explanation of the drawing]

Figure 1A, opening is a structural explanatory diagram of a double nut type constant torque breaking nut showing the prior art, Figure 2A, explanatory diagram of the state after the light nut is broken, and Figure 3A, opening is the present invention. An explanatory diagram showing an example of the above, Fig. 4 is an external view of the same, and Fig. 5 is an external appearance after constant torque failure! It is. 1: Double nut type constant torque breaking nut, 1: Lower nut, 1b: Upper nut, 2: Notch 3: Cover, 3a:
Lower cover, 3b: Upper bar, 4: Wrench, 5: Gap,
6: Groove, 7: Protrusion 8: Display color.

Claims (1)

[Claims] 1. In a double nut type constant torque breaking nut, which has a cutout groove 2 that breaks at a constant torque between the lower nut 1a and the upper nut 2b, and after the groove is broken, the upper nut acts as a lock nut. There is a gap 5 between the lower cover 3a internally fixed to the nut and the upper nut into which a wrench 4 for rotating the upper nut can be inserted, and the upper part is fitted to be rotatable with the wrench. The cover 3b is integrally formed and attached so that it can be forcibly separated, and the upper nut is broken and rotated, so that the upper cover is sheared and broken from the boundary with the lower cover and separated. A constant torque rupture nut with a display cover, characterized in that it is configured to display constant torque rupture.