JP2589066Y2 - Packing structure in fittings - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a packing structure for connecting joints, such as steel pipes, stainless steel pipes or vinyl pipes, and, at least, uses a circular arc at the tip of the packing to effectively reduce the surface pressure of the packing on the connecting pipe. To ensure that leakage from the connection portion can be prevented.

[0002]

2. Description of the Related Art As shown in FIG. 4, a conventional pipe joint of this type has a tapered packing on the inner side of the male thread portion of a joint body c having a male thread portion b engaged with a cap nut a. A packing g made of synthetic rubber or the like is compressed and deformed to the packing receiving surface d by a cap nut a screwed to the joint body c via a chuck ring e and a washer f. Conventional structures are widely known.

In this case, the packing g in this case has a trapezoidal cross section, and the upright surface h is brought into contact with the washer f on the cap nut side to reduce the inclination angle of the inclined surface i on the other side. This was adapted to the taper of the packing receiving surface d.

[0004]

A packing g having a trapezoidal cross section on the tapered packing receiving surface d described above.
In a structure in which the nut is pressed and compressed, the cap nut a
When the upright surface h of the packing g is pressed by the washer f with the male screw portion of the joint main body c and the inclined surface i of the packing g is strongly pressed against the packing receiving surface d to increase the frictional resistance. The slippage gets worse and eventually
The intermediate portion of the packing g is not obtained only modification that expands mainly.

[0005] Therefore, the amount of expansion deformation in the direction of the arrow in FIG. 1 cannot be sufficiently obtained, and packing protrudes from the space formed between the joint body c and the washer f surface, and the contact surface pressure with the pipe surface is reduced. It was found that there was a shortage. This can be easily imagined because there are many pipe joints that leak when the result of a bending fatigue test on this type of conventional pipe joint is about tens of thousands of times.

[0006]

SUMMARY OF THE INVENTION In view of such circumstances, the present invention provides a joint body having a male threaded portion for engaging with a cap nut, and having a tapered packing receiving surface on the back side of the male threaded portion. A pipe joint having a structure in which a packing made of synthetic rubber or the like is pressed against the packing receiving surface by a cap nut screwed into the joint body with a chuck ring and a washer interposed therebetween, wherein at least the joint body of the packing is provided. The cross-sectional shape of the tip part in contact with is a curved surface with a large curvature over a wide range from the tip of the lower side to the upper side.
Using the means that to.

Also, a means is used in which the cross-sectional shape of the packing in contact with the washer, that is, the rear end face is also a specific arc shape.

[0008] In addition to the above, a means has been provided in which the portion of the washer that comes into contact with the packing is convex, so that the convex step can be engaged with the opening of the joint body.

[0009]

The packing of the present invention having the above-mentioned structure has a curved cross-section at least at the end portion, so that when the cap nut is tightened to the joint body side, the cap nut is tapered through the chuck ring and the washer. Although it is pushed into the packing receiving surface side , the curved packing tip portion initially comes into contact with the tapered packing receiving surface in a line contact state, so that the frictional resistance of this portion decreases and the packing It is slippery and easily pushed deep into the connecting pipe surface to wedge-like, thus achieving a complete sealing action.

Therefore, according to the packing of the present invention, even if the volume is increased, it is sufficiently compressed by the pressing through the washer, and furthermore, the inner surface on the tip side of the packing which maintains the line contact state with the tapered packing receiving surface. The characteristic is that a component force acts to rotate in the inner diameter direction with the contact line with the packing receiving surface as a fulcrum, and the inner peripheral edge at the tip side bites into the tube surface, and a higher contact surface pressure can be obtained at this part It has the effect of

The rear end face of the packing that comes into contact with the washer has a circular cross section or a curved surface close to the cross section, because the deformability of this portion is high, so that the gap formed between the washer and the open end of the joint main body is removed. By preventing the packing from penetrating (protruding) and using a washer provided with a convex step, the convex step is engaged with the opening of the joint body and the rear end portion of the packing is securely inserted into the joint body. To make the entire volume of the packing effectively function as a seal.

This leads to a reduction in the tightening torque of the cap nut, which leads to an effect of maintaining good workability and good sealing of the connecting pipe.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description will discuss an embodiment in which the packing of the pipe joint according to the present invention has the most ideal structure, that is, the front and rear end surfaces of the packing are curved surfaces and the washer is provided with a convex step. More specifically, in FIGS. 1 and 2, reference numeral 1 denotes a joint body having a conventionally known structure;
Is a male thread portion that engages with a cap nut described later, and 3 is a tapered packing receiving surface. 4 is a cap nut having a female screw portion 5 engageable with the male screw portion 2 of the joint body;
Reference numeral 6 denotes a chuck ring, 7 denotes a washer which is pressed against the chuck ring 6, and 8 denotes a packing which is inserted into the connecting pipe 9 and inserted between the packing receiving surface 3 of the joint body 1 and the washer 7. Show.

[0014] In Thus, in the packing 8 in this embodiment, for example, a synthetic rubber, a relatively flat cross-sectional shape, except for the part of the inner peripheral surface (lower side) and the outer peripheral surface (upper side) The other peripheral surface has a curved surface configuration that is continuous at a specific curvature (see FIG. 3A). The washer 7 is a portion that comes into contact with the rear end surface of the packing 8. Is slightly convex to form a step, and this step 7 ′ can be engaged in the opening 1 ′ of the joint body 1.

According to the pipe joint according to the present invention, the members are inserted in advance so that the packing 8, the washer 7, the chuck ring 6, and the cap nut 4 are arranged in this order from the distal end side of the connecting pipe 9. Then, the connection pipe 9 is inserted into the joint body 1, and the cap nut 4 is screwed into the male screw portion 2, so that the washer 7 pushed forward through the chuck ring 6.
Presses the packing 8 in the direction of the packing receiving surface 3 and finally deforms the packing 8 as shown by a dotted line 8 'in FIG.

The deformation of the packing 8 extends over the entire inner and outer regions of the packing, and particularly, the front end portion is greatly reduced in the inner diameter direction and bites into the pipe surface to exhibit a high sealing surface pressure. Packing 8 and packing receiving surface 3
Thus, a sufficiently high sealing surface pressure is obtained while maintaining a contact state similar to a line contact with each other, and leakage from this portion is reliably prevented.

The shape of the packing 8 according to the present invention is, in addition to the shape shown in the above embodiment, at least on the packing receiving surface 3 of the joint body 1 as shown in FIGS. That the contacting tip of the packing is formed of a curved surface having a continuous curvature ,
From the lower edge to the upper edge
Even if the wide range over it is an arc with a large curvature
If this is the case, the main purpose of the present invention is to dig into the tube surface at the tip of the packing, so that the effect of increasing the surface pressure can be sufficiently achieved.

Further, the washer 7 "shown in FIG.
In the case where the packing 8 "is integrally molded with the packing 8", the packing 8 "is prevented from protruding into the opening 1 'of the joint body by forming a shallow concave groove m in a portion near the washer 7" of the packing 8 ". It is possible to do.

In the above embodiment, only the case where the retaining means of the connection pipe 9 is the chuck ring 7 has been described. However, the packing 8 of the present invention is not limited to the chuck ring, and the garter spring system is used. And other types are acceptable.

[0020]

As described above in detail, according to the packing structure of the pipe joint according to the present invention, the packing pushed in by screwing the cap nut into the joint body is in line contact with the packing receiving surface by the pressing. The packing tip is plastically deformed sufficiently along the tapered surface, and especially the inner surface of the tip protrudes greatly to the inner diameter side, and this part completely embraces the connecting pipe, so that the sealing effect is perfected. Because

In addition, since the packing volume can be increased due to the large amount of deformation of the packing as described above, the connecting pipe used is not limited to the pipe diameter to be designed, but is 3 to 8%. There is also an advantage that a sufficient sealing effect can be obtained even for connection pipes of different types (meaning a metal pipe and a synthetic resin pipe) having different outer diameters. Further, this can exert a strong sealing function even on a metal pipe whose surface is roughened by rust or corrosion, such as an underground pipe.

Incidentally, according to the results of the above-mentioned bending fatigue test performed a number of times on the pipe joint of the present invention, no leakage was observed even after 200,000 times.

[Brief description of the drawings]

FIG. 1 is a cutaway front view of the upper half of a pipe joint fitted with a packing of the present invention.

FIG. 2 is an enlarged view of a cross section in FIG.

FIG. 3 is an end view of each packing showing the shape of the packing of the present invention.

FIG. 4 is a front view showing a cutaway upper half of a pipe joint equipped with a conventional packing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Joint main body 2 Male thread part 3 Packing receiving surface 4 Cap nut 5 Female thread part 6 Chuck ring 7 Washer 8 Packing 9 Connecting pipe

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-195093 (JP, A) JP-A 61-123286 (JP, U) JP-A 64-45079 (JP, U) (58) Investigation Field (Int.Cl. ⁶ , DB name) F16L 19/00-19/08

Claims (3)

(57) [Scope of request for utility model registration] 1. A joint body having a male threaded portion engaged with a cap nut is provided with a tapered packing receiving surface on the inner side of the male threaded portion, and the joint body includes a chuck ring and a washer. In a pipe joint having a structure in which a packing made of synthetic rubber or the like is pressed against the packing receiving surface by a mating cap nut, at least a cross-sectional shape of a tip portion abutting on the packing receiving surface of the packing is changed from a lower end portion to an upper side. A packing structure in a pipe joint, characterized in that it has a curved surface with a large curvature over a range. 2. A packing joint according to claim 1, wherein a rear end face of the packing abutting against the washer has an arc-shaped cross section, and a convex step portion which can be engaged with an opening of the joint body is provided on a front surface of the washer. Construction. 3. The packing structure of a pipe joint according to claim 1, wherein the washer and the packing are integrally formed, and a concave groove is provided on a peripheral surface of the packing close to the washer.