JPH0240328Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to bolts and nuts used in underground equipment.

(Prior Art) The most common types of equipment to be buried underground include pipe joints and branch plugs for water pipes or gas pipes.
These devices use various types of bolts and nuts to tighten parts of the device. Bolts and nuts used in such equipment are susceptible to corrosion due to electrochemical reactions associated with earth currents during long periods underground. Corrosion is especially severe at the tips of bolts and threaded parts, which puts the equipment at risk of disassembly, which can eventually lead to a major accident. Corrosion of bolts as described above progresses secretly in places where people cannot see, and the rate of progress varies depending on the geology and the influence of other equipment such as electrical equipment installed in the buried area, and the corrosion state can become dangerous. It is extremely difficult to detect whether it has been reached. Therefore, sufficient corrosion protection measures must be taken for bolts at the time of burial work. Measures that have been taken in the past from this point of view include screwing cap nuts onto the tips of bolts, painting the tips and threads of bolts,
There are various types, such as those that coat the entire threaded part of the bolt and nut with tar or pitch and wrap it with resin tape, and those that use bolts and nuts made of stainless steel.

(Problems to be Solved by the Invention) However, when tightening parts of a device, members of various sizes are usually inserted into the tightening portion. Therefore, the bolts used for tightening are designed so that they can be used flexibly for both large and small intervening members.
Slightly longer versions are available, and many have slightly longer engraved screws. If such a bolt is used for tightening, the tip of the bolt that protrudes from the nut may be longer than normal, or the screw thread in the center of the bolt's shaft length may be exposed. Also often. For this reason, when attempting to screw and attach the conventional cap nut to the tip of a bolt, the bag portion of the cap nut must be made disproportionately long, and at the same time, the weight becomes excessive, making it difficult to work. lead to sexual deterioration. Moreover,
It is impossible to cover the exposed threaded portion near the center of the shaft length. Furthermore, with the above-mentioned anti-corrosion measures by painting, it is extremely difficult to make the paint film thick, so the paint film peels off when the nut is screwed, and its effectiveness can hardly be expected. Furthermore, applying tar or pitch to the threaded joint and wrapping tape over it not only requires a lot of work, but also requires the removal of tar, pitch, and tape if the equipment needs to be inspected and repaired at a later date. It takes a lot of time and work efficiency is extremely poor. Furthermore, if stainless steel bolts and nuts are used, it goes without saying that the cost will be significantly higher, but the potential of the equipment will be lower than that of the bolts and nuts, which will actually cause corrosion on the equipment side. It begins to invite people.

In view of the above-mentioned conventional drawbacks, the present invention provides sufficient protection from electrochemical corrosion caused by earth current even if buried underground for a long period of time, and requires almost no extra effort in tightening the equipment. Its purpose is to provide bolts and nuts.

(Means and effects for solving the problems) The present invention was devised to achieve the above-mentioned object, and its feature is that it is made of elastic, non-conductive synthetic resin material. A bolt with a cylindrical sleeve attached to the shaft, and a pot-shaped cap made of a highly stretchable and elastic non-conductive synthetic resin material with one end open and the other end closed to cover the tip of the bolt. and a nut having a bolt through hole, and the cylindrical sleeve includes:
At least the inner diameter of the portion that covers the unthreaded portion of the bolt is slightly smaller than the shaft diameter of the bolt so that the outer circumferential surface of the shaft portion of the bolt can be moved in the axial direction while keeping it watertight, and the length thereof is is larger than the planned distance from the threaded portion of the bolt to the device to be installed or the engaging portion with the nut, and the inner diameter of the cap is equal to or less than the outer diameter of the threaded portion of the bolt. In this manner, the outwardly projecting flange formed at the opening end is fitted into the annular groove formed on the inner circumferential surface of the bolt through hole of the nut and attached to the nut, and the length thereof is The bolt is long enough to accommodate the tip of the bolt threaded into the nut and to form an extra space between the tip and the closed end of the bolt.

(Function) With the above-described configuration, the tips and threads of bolts used for tightening equipment for water pipes and gas pipes are completely cut off from the earth current circuit, and therefore electrochemical Corrosion is extremely rare, and underground equipment can be maintained in a normal condition for many years. The extra space inside the cap attached to the nut is compressed by earth pressure when it is buried in the soil, increasing the internal pressure, preventing moisture and air from penetrating into the cap. Furthermore, by providing the extra length space, even if the amount of protrusion of the bolt from the nut changes, it is possible to accommodate this change. The inner diameter of the cap is
Since the diameter is equal to or larger than the outer diameter of the bolt, the tightening torque will not increase uselessly due to frictional resistance when tightening the bolt, and workability is extremely good.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal cross-sectional view of a bolt and nut according to a first embodiment of the present invention, showing a state in which the tightening parts 5, 5 of a pipe joint, branch plug, etc. are tightened with a bolt 1 and a nut 3. It shows. Necessary parts attached to pipe joints, branch plugs, etc. are usually interposed between the tightening parts 5 and 5, but in order to avoid complications,
Not shown. An elastic and soft cylindrical sleeve 2 is fitted onto the shaft portion of the bolt 1 .
Needless to say, the outer diameter of the cylindrical sleeve 2 is large enough to be inserted into the insertion hole 5a formed in the tightening part 5. Cylindrical sleeve 2 connects bolt 1 to nut 3
Since it is necessary to be able to move the bolt 1 in the axial direction due to the thrust generated when screwing and twisting the No. When using an M16 screw with the nominal diameter of the JIS standard, the inner diameter of the insertion hole 5a is 19 ^+1.5 _-0.5 mm, so considering the above-mentioned required strength, the wall thickness of the cylindrical sleeve 2 may be about 1 mm. . When the cylindrical sleeve 2 is fitted onto the bolt 1, it is necessary to provide watertight isolation between the periphery of the shaft of the fitted bolt 1 and the outside world. It has been made smaller. However, the small inner diameter portion may be provided only at both ends of the cylinder 2, or may be provided at a desired location between both ends and the intermediate portion. By doing this, the sliding resistance between the outer circumferential surface of the shaft portion of the bolt 1 and the inner circumferential surface of the cylindrical sleeve 2 can be reduced.
The cylindrical sleeve 2 can be easily moved while being held in a watertight state. Note that the watertight state here does not necessarily refer to a watertight state in a strict sense, but may be any state as long as corrosion of the threaded portion can be practically prevented. Furthermore, when the bolt 1 and the nut 3 are tightened, the cylindrical sleeve 2 completely extends from the threaded part of the bolt 1 to the part where it engages with the nut 3 and from the threaded part to the unthreaded part. It must be possible to adhere. Therefore, the length of the cylindrical sleeve 2 is preferably determined approximately as follows.

l = L - (h + t) where l: length of the cylindrical sleeve L: length of the threaded part of the bolt h: height of the nut t: thickness of the tightening part of the device By the way, the preferred material for molding the cylindrical sleeve 2 is is flexible polyethylene or flexible vinyl chloride. The diameter of the cylindrical sleeve 2 formed from these materials can be easily expanded by inserting a diameter expansion jig, and even if the jig is removed after diameter expansion, the diameter returns slowly to the original diameter. . Therefore, the cylindrical sleeve 2 is fitted onto the bolt 1 when the diameter thereof is expanded. Then, after a while, the cylindrical sleeve 2 returns to its original diameter and comes into close contact with the circumferential surface of the shaft portion of the bolt 1. When not in use, the cylindrical sleeve 2 is preferably fitted onto the bolt 1 to such an extent that its tip is exposed for a little longer than the height h of the nut 3.

A cap 4 is attached to the nut 3.
FIG. 2 is an exploded cross-sectional perspective view for explaining the coupling structure between the nut 3 and the cap 4. An annular groove 3a is provided on the inner periphery of the nut 3 on the side opposite to the seat surface outside the female thread. The cap 4 is made of a synthetic resin material with high stretchability and elasticity, such as rubber. Its shape resembles a jar with one end open and the other end closed. The inner diameter of the main body of the cap 4 is preferably slightly larger than the outer diameter of the threaded portion of the bolt 1, the outer diameter is smaller than the diameter of the opposite side of the nut 3, and the length is longer than the diameter of the bolt protruding from the nut 3. 1 and an extra length space 4b is formed between the closed end and the closed end. The reason why the inner diameter of the main body of the cap 4 is set as described above is to prevent the inside from coming into contact with the threaded portion of the bolt 1 and being damaged when the nut 3 is tightened, and to prevent the tightening torque from increasing unnecessarily. A fitting flange 4a projecting outward is provided around the open end of the cap 4. The fitting flange 4a has a size that fills the inside of the annular groove 3a when coupled with the nut 3, and the inner diameter of that portion is large enough to fit tightly into the threaded portion of the bolt 1. Since the cap 4 is molded from a soft material, the fitting flange 4a can be easily deformed to reduce its diameter even when pressed with fingertips. Therefore, in order to connect the cap 4 to the nut 3, the fitting flange 4a should be pinched and pressed with the tip of a finger, pushed into the annular groove 3a of the nut 3 in the reduced diameter state, and then the fingers should be released.

When tightening the tightening parts 5, 5 of a device using the bolt 1 and nut 3 made as described above, insert the bolt 1 into the insertion hole 5a of the tightening parts 5, 5, and insert the nut into the tip of the bolt 1. 3 and twisting, the seat surface of the nut 3 and the end surface of the cylindrical sleeve 2 fitted on the bolt 1 come into contact, and the cylindrical sleeve 2 pivots around the outer peripheral surface of the bolt 1 as the nut 3 screws forward. move in the direction. Shaft circumferential surface of bolt 1 and cylindrical sleeve 2
Since there is a moderate amount of sliding resistance between the inner peripheral surface of
The seat surface of the nut 3 and the distal end surface of the cylindrical sleeve 2 are in close contact with each other in a watertight manner. When the nut 3 is further screwed, the tip of the bolt 1 passes through the fitting flange 4a of the cap 4 and enters the extra length space 4b. At this time, the annular groove 3a of the nut 3 and the fitting flange 4a of the cap 4 are completely watertight.
Eventually, when the tightening parts 5 and 5 are tightened to the final stage, the proximal end of the cylindrical sleeve 2 reaches a position where it passes through the threaded part of the bolt 1, and its inner surface and the unthreaded periphery of the shaft of the bolt 1 meet. A watertight state is maintained between the surface and the surface. Therefore, all of the threaded portions of the bolt 1, including the tip, are completely isolated from the outside world and placed in a watertight state, and even if the bolt 1 is buried underground, the earth current will not flow through the watertight shielding portion of the bolt 1. will not be distributed. Therefore, the threaded part and tip of the bolt 1 will not be corroded by electrochemical reactions, and the bolt 1 and nut 3 will perform the tightening function for underground equipment for many years. The attached functions will not deteriorate.

3 and 4 are cross-sectional views showing a second embodiment and a third embodiment of the present invention. Components or parts that are the same as those in the first embodiment are given the same reference numerals.

The second embodiment shown in FIG. 3 differs from the first embodiment in that a receiving flange 2a is provided on the distal end side of the cylindrical sleeve 2. this is,
This is used when the gap between the inner circumference of the insertion hole 5a of the tightening part 5 and the outer circumference of the shaft part of the bolt 1 is smaller than the wall thickness of the cylindrical sleeve 2. In this case, the thrust when the nut 3 is screwed and twisted is transmitted to the receiving flange 2a of the cylindrical sleeve 2 via the tightening portion 5. Since the inside of the insertion hole 5a is also kept watertight by the receiving flange 2a, it goes without saying that the threaded portion of the bolt 1 located in the insertion hole 5a is protected from corrosion. Other configurations and operations are the same as in the first embodiment.

The third embodiment shown in FIG. 4 differs from the first embodiment in that a cylindrical sleeve 2 is connected to a nut 3. The coupling means are the same as those for coupling the cap 4 to the nut 3.
That is, an annular groove 3b is provided on the inner periphery of the nut 3 near the seat surface, and a fitting flange 2b is provided on the distal end side of the cylindrical sleeve 2, and the fitting flange 2b is fitted into the annular groove 3b. A reinforcing collar 3c is provided on the outer periphery of the seat surface of the nut 3 in order to compensate for the weakening of strength caused by providing the annular groove 3b. Regarding the inner diameter of the cylindrical sleeve 2, only the end portion which is not coupled to the nut 3 may be made smaller than the outer diameter of the shaft portion of the bolt 1. The cylindrical sleeve 2 is fitted onto the bolt 1 by inserting the bolt 1 into the insertion hole 5a of the tightening part 5.
Do this after inserting the In this case, fitting can be done by hand. Further, the fitting flange 2b of the cylindrical sleeve 2 may be fixed in advance using an adhesive in the annular groove 3b of the nut 3. Furthermore, if both the annular groove 3b and the fitting flange 2b are shaped to be easy to fit, such as a semicircular cross section, even if the bolt 1 is fitted with the cylindrical sleeve 2 separated from the nut 3, When the nut 3 is screwed and twisted, the annular groove 3b and the fitting flange 2b naturally fit together, and the thrust of the nut 3 is transmitted to the cylindrical sleeve 2. Other configurations and operations are the same as in the first embodiment. The sum of the lengths of the cylindrical sleeve 2 and the cap 4 is shown in FIG.
In the embodiments shown in FIGS. 2 and 3, the length of the threaded portion of the bolt 1 is equal to or greater than the length L of the bolt 1. In short, it is only necessary that the bolt 1 be set so that the threaded portion of the bolt 1 can be completely shut off from the outside world and an extra length space 4b can be formed within the cap 4 when tightening is completed.

Although the present invention has been described above with reference to three embodiments, the present invention is not limited to these examples, and its aspects may be modified in any manner without departing from the gist of the present invention. It is something. For example, the cap 4 may have a bellows shape as shown in FIG. In this way, since the amount of expansion and contraction of the cap 4 is increased, it can be used flexibly even when there is a considerable difference in size between the intervening members between the clamping parts 5, 5 in the equipment.

(Effects of the invention) According to the bolt and nut of the invention, the entire threaded part from the tip of the bolt to the unthreaded part is completely isolated from the outside world, so even if it is used for underground equipment. It is protected from electrochemical corrosion caused by earth currents, and is not damaged by gravel or mud, thus preventing the functionality of underground equipment from deteriorating over many years.

When assembling underground equipment, there is no need to take any special measures at the site, so the workability is very good and contributes to speeding up the construction work.

Since the number of parts is extremely small and the structure is simple, it is cheaper than any conventional anti-corrosion measure.

Since the cap is handled while connected to the nut, and the cylindrical sleeve is handled while connected to the bolt or nut, there is no risk that they will be lost.

The tip and threaded portion of the bolt will not be damaged even if they collide with other objects or receive external force due to vibrations during transportation.

Even if the bolts and nuts are left on the ground at a construction site, dirt will not adhere to the threads of the bolts and nuts, so there is no risk of dirt getting caught during tightening work.

When tightening equipment, it is possible to absorb the size of intervening members over a wide range and reliably tighten without affecting the specified tightening torque.

Since the cap has a length that allows an extra length space to be formed between the cap and the tip of the bolt, it can sufficiently accommodate changes in the amount of protrusion of the bolt from the nut. Therefore, even if the bolt protrudes significantly from the nut, there will be no problem in storing the bolt.

When a bolt is screwed into a nut and buried in the soil, the extra space in the cap is compressed by the earth pressure, and the internal pressure increases, allowing moisture and air to infiltrate into the cap through the meshing part between the bolt and nut. is prevented. Therefore, the oxidation of the bolt tip, which is particularly prone to corrosion, does not proceed. Further, if moisture is retained in the meshing portion between the bolt and the nut, the increase in the internal pressure of the cap causes the air in the extra length space to push out the retained moisture to the outside.

The inner diameter of the cap fitted onto the nut is equal to or greater than the outer diameter of the bolt, so
To prevent unnecessary increase in tightening torque when fastening bolts and nuts. Therefore, the efficiency of tightening the bolts and nuts is extremely high.

By achieving the effects listed above, the present invention preserves many underground equipment such as water pipes, gas pipe joints, branch valves, etc. for many years, and also improves their installation. There is a huge potential to make construction work easier and faster, thereby contributing to the development of this industry.

[Brief explanation of the drawing]

Figure 1 shows the first bolt and nut according to the present invention.
FIG. 2 is an exploded cross-sectional perspective view for explaining the coupling structure of the nut and cap shown in FIG. 4 is a vertical sectional view showing a third embodiment of the bolt and nut according to the present invention, and FIG. 5 is a sectional perspective view showing a modified example of the cap coupled to the nut. 1... Bolt, 2... Cylindrical sleeve, 3... Nut, 4... Cap, 5... Tightening part of the device.

Claims (1)

[Scope of utility model registration request] It is used for equipment buried underground, such as water pipe joints, and consists of a bolt whose shaft is covered with a cylindrical sleeve made of an elastic, non-conductive synthetic resin material, and a bolt with an elastic sleeve made of a non-conductive synthetic resin material. The cylindrical sleeve is made of a highly elastic, non-conductive synthetic resin material and has a bolt through hole to which is attached a pot-shaped cap for covering the tip of the bolt, which is open at one end and closed at the other end. , at least the inner diameter of the portion covering the unthreaded portion of the bolt is slightly smaller than the shaft diameter of the bolt, and the length thereof is such that it can move in the axial direction while maintaining the outer peripheral surface of the shaft portion of the bolt in a watertight state. is larger than the planned distance from the threaded portion of the bolt to the device to be installed or the engaging portion with the nut, and the inner diameter of the cap is equal to or less than the outer diameter of the threaded portion of the bolt. The flange formed at the opening end and projecting outward is fitted into the annular groove formed on the inner circumferential surface of the bolt through hole of the nut, and is attached to the nut, and the length thereof is as described above. A bolt and a nut, characterized in that the bolt has a length that accommodates the tip of the bolt screwed into the nut and forms an extra length space between the tip and the closed end of the bolt.