JP2003206919A - Tightening structure of powder coated nut - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tightening structure by a bolt and a nut capable of preventing powder coating from peeling off. <P>SOLUTION: In this structure for tightening an object to be tightened by screw-fitting the bag-like nut coated with powder in the bolt 11, a plastic ring 15 having self-lubricity is provided between the bag-like nut 14 and the object to be tightened. Consequently, slide of a powder coated face of the nut 14 is improved, and it is possible for even a tightening torque of about 30 to 35 N.m to reach actual use strength in the case of a pipe joint of a water pipe. Moreover, there is an advantage that unevenness of its tightening torque is small. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fastening structure using powder-coated bolts and nuts used for pipe joints such as water pipes buried underground. It is. 2. Description of the Related Art As a method of fastening an object to be fastened by using a powder-coated bolt and nut, for example, there is a pipe joint of a water pipe buried underground. An example of a conventional pipe joint is as shown in a longitudinal sectional view of FIG. In this pipe joint, the inner diameter of the tapered receiving portion 3 is set to be larger than the outer diameter of the joining tube 1, and the central portion in the axial direction expands like a drum and has a wide cavity 4 formed therein. Is prepared, and the insertion port 5 of the joint pipe 1 is inserted into the reception port 3. [0003] A rubber packing 6 for sealing is provided between an outer peripheral surface of an insertion portion of the joint body 2 and a receiving portion 3 of the joint body 2.
And pushed into the joint body 2 from behind by the pressing wheel 7. This pushing is performed by inserting a tightening bolt 11 into a bolt hole 10 of a protruding portion 8 formed on the outer periphery of an end face of the joint body 2 and a bolt hole 9 of a pressing ring 7 corresponding to the bolt hole 10 to form a bag-like nut. This is done by tightening at 12. The bag-shaped nut 12 has a cylindrical portion 12a and a large bulging diameter portion 12b.
Engages with the retaining flange 13a of the retaining ring 13 fixed to the outer peripheral surface of the joining pipe 1, thereby preventing the joining pipe 1 from coming off. The retaining ring 13
As shown in FIG. 7, a part of the circumference is open, and flanges 13b and 13c for fastening are formed at both ends of the opening, and are fastened by tightening bolts 11 and bag-like nuts 14. I am trying to do it. As a result, the outer wedge surface and the inner wedge surface of the rubber packing 6 are pressed between the tapered socket 3 of the joint body 2 and the outer peripheral surface of the joint pipe 1, and the joint pipe 1 and the joint The body 2 is held concentrically and seals fluid leakage from the connection site. In this state, the joining pipe 1
Can freely move without interfering with the inner wall of the joint body 2 in the cavity 4 of the joint body 2, can bend with respect to the axis of the joint body 2, and can be flexible. Have the property. Also, the flange 13a of the retaining ring 13 is
Can be extended and contracted within a range in which it can move between the end face of the nut 12 and the large bulging diameter portion 12b of the nut 12. [0006] Incidentally, the pipe joint is made of ductile cast iron and is buried underground, so that corrosion by soil occurs. Therefore, powder coating (film thickness 0.05-0
5 mm) to prevent corrosion and prevent corrosion. The tightening bolt 11 and the bag-shaped nut 12,
14 is also powder-coated (with a thickness of 0.03 to 0.3 mm). However, when the conventional bolt 11 and nuts 12 and 14 are tightened, when the nuts 12 and 14 are tightened, as shown in FIG. The powder coating 16 on the flange portion 13b) of the ring 13 and the powder coating 16 on the nuts 12 and 14 that come into contact therewith are peeled off, scraped off, crushed into shavings, and extruded as a result. There were problems that the surface was exposed to the outside and shavings were accumulated. For this reason, lubricating oil or the like is applied to the end surfaces of the nuts 12 and 14 that come into contact with the work to be fastened, and the lubricating oil is applied together with the shavings of the powder coating during the crushing process. At present, lubricating properties are gradually lost, contact resistance with an object to be fastened is sharply increased, and even if the nut tightening force is the same, the actual tightening state varies. When the outer diameter of the screw is 16 mm (M16), 30
There was a problem in that the state became unstable between 50 Nm and 50 Nm, resulting in good tightening and insufficient tightening. There is a problem that the variation in the tightening torque is as large as 20 N · m. For this reason, unless the tightening torque is 50 to 60 N · m, the actual strength cannot be reached unless the tightening torque is 50 Nm. SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned problems, and has been improved and removed. Therefore, the powder coating does not peel off, and the tightening operation with bolts and nuts is easy. Therefore, it is possible to provide a stable tightening structure that can be completed quickly. [0010] In order to solve the above-mentioned problems, the present invention adopts a means for fastening a powder-coated workpiece by screwing a powder-coated bag-shaped nut to a bolt. , Wherein a plastic ring having a self-lubricating property and deforming by tightening is interposed between the bag-shaped nut and the object to be fastened. By using such a plastic ring having self-lubricating properties, the powder coating surface of the nut can be smoothly slid, and in the case of a water pipe fitting, practical strength is achieved even with a tightening torque of about 25 to 35 Nm. It is possible.
Also, there is an advantage that the variation in the tightening torque is small. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below with reference to the embodiments shown in the drawings. The same reference numerals as those in the conventional case denote the same members. 1 and 2 relate to an embodiment of the present invention. FIG. 1 shows a case where a plastic ring 15 having a self-lubricating property and being deformed by tightening is applied to a nut 12 for fastening the pressing wheel 7. FIG. 2 is a longitudinal sectional view of a pipe joint portion in a temporarily tightened state, and FIG.
It is a front view to which No. 5 was applied. The plastic ring 15 may be made of, for example, nylon 6 or the like, which is deformed by tightening and has excellent self-lubricating properties. Thickness is 0.3 ~
What is necessary is just to use the thing of about 1.8 mm. 0.
If the thickness is less than 3 mm, the plastic ring 15 cannot withstand practical strength. Also 1.
If it exceeds 8 mm, deformation due to tightening is unlikely to occur, it is impossible to prevent over tightening, and furthermore, the plastic part left after completion of tightening undergoes aging due to pressure, and the bolt and nut loosen. This is because it will occur. The nut 14 is moved from the state shown in FIG.
, First, the distance between the flanges 13b and 13c of the retaining ring 13 is reduced, and the state shown in FIG. Then, when further tightening is performed, the convex portions 16 on the facing surface side outside the flange come into contact with each other, and the target tightening is obtained. FIG. 4 is a longitudinal sectional view of the nut 14 after tightening. When the nuts 14 are further tightened after the projections 16 have come into contact with each other, as shown in FIG. It can be easily detected. When the plastic ring 15 is further tightened, the plastic ring 15 frays and the torque rapidly increases, so that excessive tightening can be prevented. The detection of excessive tightening due to the deformation of the plastic ring 15 can be changed by changing the thickness of the plastic ring 15 within the range of 0.3 to 1.8 mm, thereby changing the tightening torque when the deformation occurs. It is. Therefore, the thickness of the plastic ring 15 may be set according to the target tightening torque. The thickness of the plastic ring 15 is 1.8 m
m, the deformation occurred at 30 to 35 N · m. Further, it was worn out at 120 N · m and could not be tightened. FIG. 5 shows an experimental result for confirming the effect of the plastic ring 15 in this embodiment. Two samples were compared for the conventional case where the plastic ring 15 was not mounted and the case of the present embodiment where the plastic ring 15 was mounted. According to the result, in the conventional case, when the nut 14 is tightened, the powder coating 16 on the end face in contact with the flange 13b is peeled off and extruded.
b, and if the tightening torque is not more than 60 N · m, the retaining ring 13 cannot be rigidly fixed to the joint pipe 1, and the joint pipe 1 may come off. Moreover,
In order to obtain a fastening force that can withstand practical strength, 60-80
It became clear that a tightening torque of N · m was required, and the variation was large. On the other hand, in the case of the present embodiment, the plastic ring 15 is mounted between the nut 14 and the flange 13b of the retaining ring 13, so that the nut 14 slides well and is tightened to 30 N · m or more. If the torque is used, the retaining ring 13 can be fastened to the joint pipe 1 with a sufficient tightening strength to withstand practical strength, and there is no fear that the joint pipe 1 comes off. Moreover, in order to reach the fastening force that can withstand practical strength,
A tightening torque of 30 to 35 N · m is sufficient, and the variation is as small as 5 N · m. Incidentally, the present invention is not limited to the above-described embodiment, and can be appropriately changed. For example, the plastic ring 15 may be formed integrally with a cylindrical flange having a predetermined height and externally fitted to the nut 14. The flange may rise in a U shape from the peripheral side of the plastic ring 15 or may rise from the middle of the plane. With such a configuration, when the nut 14 is removed, the plastic ring 15 comes off integrally with the nut 14 and does not separate, so that there is an advantage that it is convenient for reassembly and the like. As described above, according to the present invention,
In the bolt, the powder coated bag-shaped nut is screwed on to fasten the powder-coated workpiece, and the self-lubricating property between the bag-shaped nut and the workpiece is tightened. A plastic ring that causes deformation is interposed. By using a plastic ring that has self-lubricating properties and deforms when tightened, the powder-coated surface of the nut can be slid better, and in the case of a water pipe fitting, 30 to
It is possible to reach practical strength even with a tightening torque of about 35 N · m. Another advantage is that the variation in the tightening torque is small. Further, there is an advantage that the tightening work of the bolt and the nut is released from heavy labor, the work becomes easy, and the construction time is shortened. Further, paying attention to the fact that the deformation according to the thickness of the plastic ring and the tightening torque are proportional, by setting the thickness of the plastic ring, it is possible to visually confirm that the tightening torque has reached the target. It is also possible to confirm. In addition, the plastic ring is worn out too much and can be visually confirmed and not overtightened,
It is possible to prevent excessive tightening.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a pipe joint showing a fastening structure of a pressing wheel according to an embodiment of the present invention. FIG. 2 is a front view showing a fastening structure of a retaining ring according to one embodiment of the present invention. FIGS. 3A to 3C are partial enlarged front views each showing a fastening state of a nut of a retaining ring in a time-series manner, according to an embodiment of the present invention. FIG. 4 is a longitudinal sectional view of a nut of a retaining ring according to an embodiment of the present invention, showing a state after fastening. FIG. 5 is a drawing showing changes in tightening torque showing experimental results showing a comparison between the present invention and a conventional technique. FIG. 6 is a longitudinal sectional view of a pipe joint showing a conventional fastening structure for a press wheel. FIG. 7 is a front view showing a conventional retaining ring fastening structure. FIG. 8 is a longitudinal sectional view of a nut of a retaining ring showing a state after the conventional fastening. [Description of Signs] 1 ... joining pipe, 2 ... joint body, 4 ... cavity, 6 ... rubber packing, 7 ... pressing ring, 11 ... tightening bolt, 12 ... pressing ring nut, 14 ... snap ring nut, 15 ... plastic ring

Claims (1)

Claims: 1. A powder-coated bag-shaped nut is screwed onto a bolt to fasten a powder-coated object to be fastened. A fastening structure for a powder-coated nut, characterized by interposing a plastic ring having a self-lubricating property and being deformed by tightening.