JPH0210326Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a tightening bolt, and more particularly, to a tightening bolt having a measuring rod extending vertically through the center of the bolt for measuring the elongation of the bolt.

When tightening a bolt, in order to check the proper tightening force, there is a tightening bolt with a measuring rod running through the center of the bolt to measure the elongation of the bolt. As shown in FIG. 1, a through hole 2 is bored in the center of the bolt 1 in the axial direction.
A measuring rod 3 screwed or fitted into this through hole 2 with the tip 1a of the bolt 1 is inserted into the threaded portion 3a.
The head 1b of the bolt 1 is passed through without being restrained except for the head 1b of the bolt 1, and its upper surface 3b
It has been polished in advance to match the upper surface 1c of the.

When such a tightening bolt 1 is tightened until the desired tightening force is obtained, the bolt 1 will elongate as shown in Figure 2a, but since the measuring rod 3 is not in a restrained state with the bolt 1, it will initially The length of is maintained, and a dent amount A is created in the head 1b of the bolt 1. Therefore, as shown in FIG. 2b, an operator uses a surface plate 4 or the like to align the scale 5a of the dial gauge 5 with the pointer 5 of the gauge 5 on the lower surface 6a of the gauge base 6.
After adjusting so that b is zero, place the dial gauge 5 on the top surface 1c of the bolt 1 and slide it back and forth and left and right until the pointer 5b moves, that is, until the measuring tip 7 reaches the top surface 3b of the measuring stick 3. The elongation of the bolt 1 is measured by moving the bolt 1 (see FIG. 2c) and displaying the amount of dent A with the pointer 5b. Then, it is confirmed whether this measured value is a value that allows the desired tightening force to be obtained.

By the way, if an insufficiently tightened bolt hits a device that vibrates strongly, such as a diesel engine, it may cause premature damage or create a dangerous situation.
Under-tightening or forgetting to tighten bolts is unacceptable. However, with the above-mentioned tightening bolt, the top surface of the measuring rod becomes recessed from the top surface of the bolt due to the bolt elongation, so even if it is screwed into a specified location, it cannot be tightened to the point where it exerts the proper tightening force. There is a problem in that it is not possible to approximately confirm whether or not the dent is present only from the presence of the dent without using a dial gauge after the fact.

This invention was developed to solve the above-mentioned problems, and even an operator without a dial gauge can check whether the tightening bolt screwed into the tightening point is close to the normal tightening condition. ,
To provide a tightening bolt whose appearance can be easily checked.

The feature of this bolt is that it is a tightening bolt that has a recessed part around the measuring rod in the head of the bolt with a depth approximately equal to the elongation when the bolt is properly tightened.

Hereinafter, the tightening bolt 20 of the present invention will be described in detail based on its embodiments.

In FIG. 3, a through hole 21 that runs vertically in the axial direction is bored in the center of the tightening bolt 20.
A measuring rod 22 for measuring the elongation of the bolt 20 due to the tightening force is passed through the through hole 21 vertically. This measuring rod 22 has a threaded end 22a.
The bolt 20 is threadedly fixed or fitted into the tip 20a of the bolt 20, and is not restrained in any other way. The upper surface 20c of the head 20b, which is the measurement reference surface of the tightening bolt 20, and the upper surface 22b of the measuring rod 22 are polished in advance so that they match, and the measuring rod 20c on the upper surface 20c of the head 20b of the bolt 20 is polished in advance. A depth B1 approximately equal to the elongation when the bolt 20 is properly tightened around the
A concave portion 23 is carved therein. Therefore, when the bolt 20 is tightened with a predetermined tightening force, the top surface 22b of the measuring rod 22 and the bottom surface 23a of the recessed portion 23 are in a state of almost matching, so that the head of the bolt 20 is tightened as shown in FIG. When the worker's fingertips 24 are placed on the concave portion 23 of the portion 20b, it is possible to check with the fingertips 24 whether the bolt is tightened with a predetermined tightening force.

Since the present invention has the above-described configuration, the elongation of the tightening bolt can be easily checked in the following manner.

First, the aforementioned tightening bolt 20 is tightened until a predetermined tightening force is generated. Next, the fourth
As shown in the figure, the pointer 26a of the gauge 26 is adjusted to zero on the scale 26b on the lower surface 27a of the base 27 of the dial gauge 26 using a surface plate 25 or the like, and the base 27 is The bolt 20 is placed on the reference surface 20c of the head 20b, and the dial gauge 26 is slid on the upper surface 20c in front and back and left and right until the tip 28a of the measuring tip 28 is located on the upper surface 22b of the measuring rod 22. The amount of elongation of the bolt 20 due to tightening, that is, the upper surface 20c
The tightening force of the bolt 20 can be confirmed by measuring the amount of dent B2 generated between the upper surface 22b of the measuring rod 22 and the upper surface 22b of the measuring rod 22.

In addition, when attempting to roughly check the tightening condition after the fact, as shown in FIG.
When the worker's fingertip 24 is placed on the surface, the amount of level difference between the bottom surface 23a and the top surface 22b of the measuring rod 22 can be confirmed with considerable accuracy by feeling the fingertip 24. Therefore, it is possible to approximately confirm whether or not the proper tightening force is being generated.

It goes without saying that the relationship between the amount of bolt elongation and the tightening force has been confirmed theoretically and experimentally in advance.

If this kind of confirmation work becomes possible, it will be possible to check whether the bolt is being tightened with the specified tightening force after the fact, instead of just seeing a dent in the measuring rod from the top of the bolt due to bolt elongation, as experienced with conventional tightening bolts. The problem of not being able to make any other judgments has been resolved, and it is now possible to easily find bolts that are insufficiently tightened or bolts that have been forgotten to be tightened.

FIG. 6 shows a different embodiment of the tightening bolt 30.
A cross-sectional view is shown. This tightening bolt 30 is attached to a bolt head 30b around the upper surface 22b of the measuring rod 22.
A recess 23 with a depth B1 approximately equal to the elongation when the bolt 30 is properly tightened is formed, and a recess 31 is formed on the lower surface 27a of the base 27 of the dial gauge 26. A cylindrical guide surface 32 into which the bolt 30 is guided is formed concentrically with the bolt 30 on its head 30b. Further, as in the above embodiment, the top surface 30 of the bolt head serving as a reference surface is also provided.
c and the upper surface 22b of the measuring rod 22 are polished in advance so that they match.

When the bolt 30 is tightened, only the bolt 30 expands and the length of the measuring rod 22 does not change, so that a dent amount D is generated between the two surfaces 22b and 30 described above. The amount of depression D is measured by using a surface plate (not shown) on the bottom surface 31a of the depression 31 carved in advance on the base 27 of the gauge 26, so that the pointer 26a of the gauge 26 reaches zero on the scale 26b. If the base 27 is fitted into the cylindrical guide surface 32 formed on the outer periphery of the bolt head 30b, the tip 28a of the measuring head 28 of the gauge 26 will naturally align with the measuring rod. 22, so all you have to do is read the scale 26b at that time. Further, if it is desired to inspect the tightening force after the fact, the approximate tightening state can be confirmed by placing the operator's fingertip 24 on the recessed portion 23 as shown in FIG.

Note that the guide surface 32 is not limited to the upper part of the head 30b of the bolt 30, but is also provided on the gauge base 27.
If the concave portion 31 of can be made deep,
Although not shown, it goes without saying that it may be provided on the side surface 30d (see FIG. 6) of the head 30b.

As explained in detail above, the present invention uses a tightening bolt in which a recessed part with a depth approximately equal to the elongation when the bolt is properly tightened is carved around the measuring rod of the bolt head. Therefore, it is possible to easily discover after the fact that bolts used in places with strong vibrations, such as diesel engines, are insufficiently tightened or forgotten. As a result, insufficient or forgotten bolt tightening can be quickly addressed, ensuring safe operation of diesel engines, etc.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional tightening bolt, Figure 2 is a sectional view of a conventional tightening bolt.
Figure a is a sectional view of the tightening bolt in the tightened state, Figures 2 b and c are diagrams of the conventional tightening force measurement state,
Figure 3 is a sectional view of the tightening bolt of the present invention, Figure 4 is a diagram of the tightening force measurement state of the present invention, Figure 5 is a diagram of the tightening force confirmation state with a fingertip, and Figure 6 is the tightening force measurement state of a different embodiment. 7A and 7B are state diagrams for checking the tightening force of different embodiments. 20, 30...Tightening bolt, 20b, 30b
... Bolt head, 20c, 30c ... Reference plane of bolt head, 22 ... Measuring rod, 22b ... Upper surface, 23 ... Recessed part.

Claims (1)

[Claim for Utility Model Registration] A measuring rod for measuring the elongation of the bolt is inserted vertically through the center of the bolt, and before tightening, the reference plane of the bolt head and the top surface of the measuring rod match. A tightening bolt that has been polished to a similar level is characterized in that a recessed part with a depth approximately equal to the elongation when the bolt is properly tightened is carved around the measuring rod of the head of the bolt. Tightening bolt.