JPS621125B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in shaft-like (or rod-like) fasteners such as studs and bolts.

To tighten studs and bolts to other parts, the male threaded part of the stud or bolt is screwed into the threaded hole of the other part.
If you can determine whether studs and bolts have been tightened to the specified tightening strength, you can check for poor tightening such as loosening due to insufficient tightening force or breakage of studs and bolts due to excessive tightening. ,
This is important for performing tightening work in proper conditions.

In order to meet such demands, shaft-shaped fasteners have been proposed, for example, as disclosed in US Pat. No. 2,413,797. This shaft-shaped fastener consists of a bolt that passes through a through hole in the axial direction.A split groove is provided at the tip of the bolt opposite to the bolt head, and a rod is inserted into the through hole. One end is fixed to the through hole on the bolt head side, and the free end of the rod protrudes from the through hole. When the bolt is tightened, tightening stress is applied to the bolt, causing the bolt to expand due to tension. Then, the free end of the protruding rod enters the slot of the through hole, and by visually checking the extent of the entry from the outside, the degree of tightening stress acting on the bolt can be confirmed. The tightening force is adjusted to ensure that the bolt is tightened to the appropriate tightening strength.

This type of structure has the disadvantage that the tightening force is not constant, as the judgment of the tightening force varies depending on the skill level of the operator who visually recognizes the relative movement of several tens of microns between the rod and the bolt. In addition, since the free end of the rod is located at the tip of the bolt, depending on conditions such as the tightening location, it may be difficult to visually check the movement of the rod. If the free ends of bolts and rods are made of the same metal material, it may be difficult to tell them apart, and if both are dirty with oil or other dirt, the movement of the free end of the rod may not be visible. This has the disadvantage that it is not very practical.

Furthermore, as a well-known technology, the 1957 edition “FASTENERS HANDBOOK (REINHOLD
92 of “PUBLISHING CORPORATION, USA)”
For the bolts described on this page, the protrusion of the central shaft is checked using a dial gauge, and the optimal tension is applied to the bolts.

This seems to be good when trying to measure accurately, but it is important to check when using it in places where bolts are actually used, which have complex structures and require precision tightening force. At the same time, there is a problem in that measurement errors occur depending on the position of the dial gauge, installation location, etc., and there is also the problem that maintenance and inspection must be done visually (reading the dial gauge).

In addition, Japanese Patent Publication No. 51-13672 uses a central axis and a light-absorbing fluid to determine the optimal tightening force for bolts, and it is recommended that the fluid itself be used in locations that are used outdoors for a long period of time and that are subject to relatively large amounts of vibration. Considering weather resistance, fluid leakage, etc., problems arise in terms of reliability, which also needs to be checked visually.

On the other hand, Japanese Patent Publication No. 53-14695 is known, which utilizes the tension of the center shaft as a fastening steel wire, but this method does not provide the optimum tightening force to the bolt, but rather provides the optimum tightening force for the center shaft (the fastening steel wire). This is a tightening device that generates a force, and there is a big difference in terms of reliability of the bolt from the present invention, which manages the optimal tensile force (stress) of the bolt itself.

SUMMARY OF THE INVENTION Therefore, the present invention solves the drawbacks of the known structures described above, and allows the operator to easily and reliably determine the tightening state during tightening work, thereby enabling the operator to tighten in an appropriate state. The tightening condition can be checked even after installation, and defective parts due to changes over time, such as loosening of tightening or partial breakage, can be checked reliably and easily by hand or other tools. The purpose of this invention is to provide shaft-shaped fasteners such as studs and bolts.

Moreover, it is impossible to infer the present invention from the above-mentioned known techniques etc. in terms of the effects of the present invention.

Next, the present invention will be explained in detail with reference to illustrated embodiments.

Stud (headless bolt) 10 shown in Figure 1
A through hole 11 penetrates the entire length in the axial direction, and male threads (threads) 12 and 13 are formed on the outer circumferential surface of both ends in the axial direction. These male screws and the through hole 11 share a central axis 14.

A pin 15 is inserted through the through hole 11, and both left and right ends of the pin 15 protrude from both ends of the stud 10. Nut-shaped contacts 16 and 17 are fixed to the protruding end of the pin 15.
6 and 17 face both end surfaces 18 and 19 of the stud 10. The contacts 16 and 17 are separate from the pin 15, and are forcibly fitted and fixed to the protruding end of the pin 15 by means such as swaging. At least one of the contacts 16, 17 is fixed to the pin 15 after the pin 15 is inserted into the through hole 11. It is located loosely between the two.

The pin 15 is inserted into the through hole 11 so that it can slide and rotate freely, and the stud 10 can freely rotate around the pin 15.

When no stress is applied to the stud 10, the contacts 16 and 17 located at the left and right protruding ends of the pin 15 are spaced apart from both end surfaces 18 and 19 of the stud 10 with a slight gap as described above. Therefore, the internal dimension between the contacts 16 and 17 is longer than the entire length of the stud 10, and the contact and the pin are aligned with the center axis 14 as an axis. It is designed to rotate with respect to the stud 10. Then, when a tensile stress is applied to the stud 10 and the stud 10 expands in the axial direction, the total length of the stud 10 at the time of expansion is
The stud 10 extends to a length equivalent to the internal dimension between 6 and 17, or longer, and extends to both end surfaces 1 of the stud 10.
8 and 19 come into contact with the contacts 16 and 17 and press these contacts, and as a result, the contacts 16 and 17 and the pin 15 are in a state where they cannot rotate due to the axial extension and pressure of the stud 10. Become. Therefore, when tightening the stud, whether or not the stress acting on the stud has reached a predetermined value (threshold value) can be determined by checking whether the contact can freely rotate relative to the stud. It will be possible. If the contactor cannot be rotated or rotated by hand, it means that a predetermined stress has been applied to the stud.

In this way, the slight elongation of the stud or bolt that occurs when the stress reaches a predetermined value can be accurately perceived without the need for any special technology by using a binary representation of whether or not the contact can rotate.

The embodiment of FIG. 2 has a bolt 1 instead of a stud.
10, a male thread 112 is carved on the outer peripheral surface of the tip on the opposite side of the head 120, a pin 115 is inserted into the through hole 111, and the protruding end of the pin 115 has a , each contact 11
6 and 117 are fixed and face the left and right end surfaces 118 and 119 of the bolt 110 with a slight gap therebetween. Then, when the bolt 110 is screwed into the screw hole of another member via the male screw 112 and tightened,
A tensile stress acts on the shaft body of the bolt 110, and when the value of this stress reaches a predetermined value, the shaft body of the bolt 110 expands in the axial direction, and as a result, the bolt 11
Both end surfaces 118 and 119 of contactor 1
16 and 117 and press them, so that the contacts 116 and 117 and the pin 115 no longer rotate about the shaft 114. Each contact 116, 11
7 no longer rotate, it can be determined that the tensile stress acting on the bolt 110 has reached a predetermined value, and it can be seen that sufficient tightening strength has been secured.

In the first and second embodiments shown in Figs. 1 and 2, contacts made of nut-shaped or other annular bodies of the same shape are fixed to both ends of the pin, but one contact is integrated with the pin or the cotter pin. (For example, the head of the pin is used as one contact.) Alternatively, a separate contact may be attached to the other end of such a headed pin.

Also, unlike the previous embodiment, the pin and one contact are installed in a manner that they cannot rotate relative to a fastener such as a stud or bolt, and only the other contact is installed in a state where no stress is applied to the stud or bolt. may be allowed to rotate freely. In this way, in order to allow only the other contact to freely rotate, the non-rotatable contact is the head of a pin, and the contact is loosely fitted between this head and one end face of the stud or bolt. That's fine.

In the third embodiment of FIG. 3, the pin 215 is connected to the bolt 2.
10 blind holes 211 (from the head 220 to the central axis 214
the tip 21 of the pin 215.
5a in the deep part of the blind hole 211, and then insert the pin 215.
is attached to the bolt 210 so as not to rotate, while the pin 215 and the bolt 210 are allowed to slide relative to each other except for the tip 215a, and the head 215 of the pin 215 protrudes from the bolt 210.
A washer-like contact 216 is loosely fitted between the bolt 210 and the end face 218 of the bolt 210, and the reference numeral 212 indicates a male thread 221 indicating a protective cap. Contact 21
6 has a head 215b that is loosely fitted into the shank of the integral pin 215, and rotates freely when no stress is applied to the bolt 210, as in the previous embodiment, and when tensile stress is applied to the bolt 210, it Due to the elongation of the bolt 210 due to reaching a predetermined value, the end face 218 of the bolt 210 and the pin 2
15 and stops rotating, which indicates that a predetermined tensile stress has been applied to the bolt 210.

The embodiment of FIG. 4 is also similar to the third one, except that the protective cap 321 and the tip 3
15b and the shape of the contactor 316, and the method of fixing the tip 315a of the pin 315 are different. That is, in the third embodiment, the cap is fitted to the outer periphery of the head 220 to attach the cap, whereas in this embodiment, the cap is fitted to the inner peripheral surface 323 of the recess formed in the head 320, and the cap is fitted to the outer periphery of the head 220. Head 315b is bolt 3
It is screwed and fixed to 10. FIG. 4 shows the state in which the male screw 212 is screwed into the nut 322 and tightened, and 314 is the central axis, and 311 is a blind hole.

In each of the above embodiments, the pin has the same coefficient of thermal expansion as the shaft-like fastener such as a pin or bolt;
or a similar one, and both are preferably molded from the same metal material, thereby allowing both to have the same coefficient of thermal expansion.

When tightening bolts or studs,
At least one of the contacts described above is located near the operator's hand, so it is easy to check whether the contact can rotate. By checking whether the contact can rotate, the tightening force of the bolt or stud can be adjusted to the specified level. It is possible to know whether the value is within the specified range, and to tighten bolts and studs with appropriate tightening strength. In addition, the tightening condition of bolts and studs after tightening and the durability of bolts and studs can be inspected by periodically or irregularly checking whether or not the contactor can rotate.
If a destructive phenomenon such as a crack occurs in the bolt or stud itself, the contactor rotates.
Defects can be easily discovered, appropriate corrective measures can be taken, and defects that can lead to serious accidents can be checked to prevent accidents.

[Brief explanation of the drawing]

Figures 1 to 4 are the first diagrams of this invention, respectively.
It is a sectional view showing a fourth example from an example. 10...Stud, 110,210,310...Bolt, 11,111...Through hole, 211,311...
Blind hole, 12, 13, 112, 212, 312...male thread, 14, 114, 214, 314... central axis,
15, 115, 215, 315...pin, 16, 1
7, 116, 117, 216, 316... contactor,
18, 19, 118, 119, 218...end surface, 1
20, 220, 320...Bolt head, 322...
Natsuto.

Claims (1)

[Claims] 1. A pin protrudes from at least one end in the axial direction of a stud, bolt, etc., a contact is attached rotatably about a central axis, and a threshold value of a tightening force is applied to the stud, bolt, etc. is set, and installed so as to face the end of the stud or bolt, etc. with an interval corresponding to the elongation of the stud or bolt due to the tensile stress, and the stud or bolt, etc. A stud, bolt, etc., characterized in that the threshold value of the tightening force of the stud, bolt, etc. is detected by the contact being pressed against the end portion and unable to rotate due to extension in the direction of the stud, bolt, etc. Tightening force management device. 2. In the tightening force management device for a stud, bolt, etc., as set forth in claim 1, the pin protruding from one end of the stud, bolt, etc. is arranged so as not to be interlocked with the elongation action of the stud, bolt, etc. A tightening force management device for studs, bolts, etc. installed in