JP2019190529A - Coupling type pipe joint - Google Patents

Abstract

To provide a coupling type pipe joint capable of accomplishing a high anti-pulling force (grip force) even in the case that a metallic pipe has a thin pipe thickness and a high pressure is applied to it.SOLUTION: This invention relates to a coupling type pipe joint comprising a cylindrical coupling main body (casing 2) formed with a slit along a pipe axis direction that can be fastened by fastening means 20, this coupling main body outwardly fitted over abutted pipe ends of two metallic pipes to connect these pipe ends to each other. The coupling main body (casing 2) includes several pairs of grip rings 3 where ring part is cut to enable its diameter to be reduced and having a relatively high hardness cut into said metal pipes, a cylindrical rubber sleeve 4 interposed in these grip rings 3 to seal fluid in said metal pipes to be connected. Said several pairs of grip rings 3 are arranged at each of the pipe ends while a predetermined space X being left.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a coupling-type pipe joint that connects metal pipes that are butted together, and more particularly, to a coupling-type pipe joint that connects stainless steel pipes to each other.

  Conventionally, a mechanical pipe joint that connects metal pipes by a mechanical method is known. Various types of mechanical pipe joints such as a press type, a pipe expansion type, a nut type, a rolling screw type, a plug-in type, and a coupling type (strab grip type) are known.

  Among these, the coupling type pipe joint accommodates a rubber sleeve and a grip ring in the coupling body, tightens the coupling body with bolts and nuts, and bites this grip ring into the pipe end of the metal pipe, The tube end portion is sealed. This coupling type pipe joint has an excellent feature that metal pipes can be easily connected to each other without the need for secondary processing such as threading or grooving at the end of the pipe to prevent the metal pipe from coming off.

  However, on the other hand, the pipe end is not subjected to secondary processing to prevent it from coming out, so when a high pressure is applied to the pipe, it has a high pull-out prevention force (grip force) to prevent the metal pipe from coming out of the pipe joint. : Tensile strength in the tube axis direction).

  For example, in Patent Document 1, the outer peripheral surface position where the pipe ends of the pipe 30 are abutted is surrounded by a housing 11 having a substantially C-shaped cross section that houses a seat lock mechanism 20 having a seat ring 21, a lock ring 22, and the like. A pipe joint 10 for joining pipes 30 and 30 together by fastening both circumferential ends 12 and 12 of the housing 11 with fastening members 18 such as bolts, and one of the both ends 12 and 12 of the housing 11 Alternatively, a pipe joint 10 is disclosed in which contact parts 13 are provided on both sides, and the contact part 13 is brought into contact with the other contact part 13 or the other end part 12 of the housing 11 when the housing 11 is tightened. (See claim 1 of patent document 1, paragraphs [0015] to [0030] of the specification, FIGS. 1 and 2 of the drawings, etc.).

  The pipe joint 10 described in Patent Document 1 can easily regulate the tightening torque and perform tightening with an appropriate tightening amount to reliably seal the pipe, and is stable even when joining pipes having different diameters. It is said that joining can be performed in a sealed state by tightening.

  Further, in Patent Document 2, pipes P are joined by a lock ring mechanism 160 that is fitted in the housing 151 by fastening both ends of a cylindrical housing 151 having a C-shaped cross section surrounding the sealing sleeve 161 with a bolt fastening member 168. In the joint for diameter reduction, a joint for diameter reduction provided with a slit 154 having an appropriate length along the circumferential direction from one or both ends of the housing 151 is disclosed (Patent Document 1 Patent). Claim 1, paragraphs [0027] to [0055] of the specification, FIG. 2, FIG. 3, FIG.

  The joint for diameter reduction of Patent Document 2 has an error in the actual pipe diameter when joining pipes having the same nominal diameter, or different diameter pipes having different nominal diameters or different materials such as metal and resin. Even when the pipes are joined, it is said that they can be joined firmly while exhibiting high sealing performance while working the lock ring function.

  However, coupling-type pipe joints such as the pipe joint 10 described in Patent Document 1 and the joint for reducing diameter described in Patent Document 2 are thick when connecting metal pipes having a general hardness. Therefore, when connecting thin metal pipes having a small thickness and high hardness such as stainless steel pipes, there is a problem that a desired pull-out preventing force cannot be achieved.

  For example, when connecting stainless steel pipes for fire extinguishing equipment, it has been necessary for the coupling type pipe joints to clear predetermined pressure tests, bending tests and tensile strength tests according to the joint performance standards of the Fire Service Act. In this way, when connecting stainless steel pipes with a coupling type pipe joint, a high pressure is applied to the pipes, and the thickness of the stainless steel pipe generally used is 2 mm or less and 3 mm at the maximum, and It was characterized by high hardness and very hardness. For this reason, in the coupling type pipe joint, even if the force for simply tightening the casing (coupling body) with bolts and nuts is increased, the steel pipe itself is bent and the grip ring does not penetrate deeply into the stainless steel pipe, and the desired high There was a problem that the pull-out prevention force (grip force) could not be achieved.

JP 2003-172485 A JP 2008-75884 A

  Therefore, the present invention has been devised in view of the above-mentioned problems, and the object of the present invention is to have a high pulling-inhibiting force even when the metal tube is thin and high pressure is applied. It is an object of the present invention to provide a coupling type pipe joint that can achieve (grip force).

  A coupling type pipe joint according to a first aspect of the present invention has a cylindrical coupling body that is formed with a slit along a tube axis direction and can be tightened by a tightening means, and the coupling body includes two metal tubes. A coupling type pipe joint that is externally fitted across the butted pipe ends and connects these pipe ends, and a part of the ring shape is notched in the coupling body so that the diameter thereof can be reduced. A plurality of pairs of grip rings having relatively high hardness that bite into the metal pipe, and a cylindrical shape that seals a fluid in the pipe of the metal pipe that is interposed in and connected to these grip rings. And a plurality of grip rings are provided at each tube end at a predetermined interval.

  The coupling type pipe joint according to a second aspect of the present invention is characterized in that, in the first aspect, a guide ring is interposed between each pair of the grip rings.

  The coupling type pipe joint according to a third aspect of the present invention is the first aspect or the second aspect of the invention, wherein the inner side of the base end portion of the grip ring inside each pair has a triangular cross section that holds the inclination angle of the grip ring. The triangular ring is provided.

  According to a fourth aspect of the present invention, there is provided the coupling-type pipe joint according to any one of the first to third aspects of the invention, wherein the rubber sleeve is disposed in the pipe inside the notched portion of the grip ring inside each pair. A protection ring is provided to prevent the pressure from being pushed out by the pressure of.

  In a coupling type pipe joint according to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects of the invention, the rubber sleeve is provided with an annular spring that increases the adhesion with the metal pipe in the vicinity of both ends. It is characterized by.

  According to 1st invention-5th invention, even when the pipe | tube thickness of a metal pipe is thin and a high pressure is applied, for example, even when connecting the stainless steel pipes for fire extinguishing facilities, a metal pipe is dented. The grip ring can be bitten into the metal tube to a predetermined depth without being bent or bent. For this reason, there is no need for secondary processing such as threading or grooving at the pipe end, and a high pull-out preventing force (grip force) can be achieved in a coupling type pipe joint that can easily connect metal pipes to each other.

  In particular, according to the second aspect of the invention, since the guide ring that holds the gap between each pair of grip rings is interposed, the outer grip ring is displaced inward, or the grip ring is tilted to reduce the inclination angle. The grip ring can be surely bitten into the metal tube without any trouble.

  In particular, according to the third aspect of the invention, since the triangular ring having a triangular cross-section that holds the inclination angle of the inner grip ring is provided, the inner grip ring is prevented from falling, and the grip ring is more reliably secured. It can bite into a metal tube.

  In particular, according to the fourth invention, since the protection ring is provided, it is possible to prevent the rubber sleeve from being pushed outward by the pressure in the pipe. For this reason, the connection part of metal pipes can be reliably sealed with a rubber sleeve, and there is little possibility that the fluid flowing in the pipe leaks out.

  In particular, according to the fifth invention, since the annular springs are mounted in the vicinity of both ends of the rubber sleeve, the adhesion between the metal tube and the rubber sleeve can be increased, and the sealing force can be further improved. .

It is a perspective view showing a coupling type pipe joint concerning an embodiment of the present invention. It is the front view which looked at the coupling type pipe joint same as the above along the pipe-axis direction. It is a left view of a coupling type pipe joint same as the above. It is an AA line end view of Drawing 2 showing a coupling type pipe joint same as the above. It is a perspective view which shows the grip ring of a coupling type pipe joint same as the above. It is a fragmentary sectional perspective view shown in the state where a part of rubber sleeve of a coupling type pipe joint same as the above was cut along the direction of a pipe axis. It is a perspective view which shows the triangular ring of a coupling type pipe joint same as the above. It is a perspective view which shows the guide ring of a coupling type pipe joint same as the above. It is a perspective view which shows the protection ring of a coupling type pipe joint same as the above. It is explanatory drawing which shows the fastening state of the conventional coupling type pipe joint by an end view, (a) has shown before fastening, (b) has shown after fastening. It is explanatory drawing which shows that it does not reach the amount of biting as designed because a steel pipe dents inside, (a) is a design state, (b) has shown the actual state. It is explanatory drawing which shows the case where a pair of two grip rings are mounted on the conventional coupling type pipe joint in an end view. It is explanatory drawing which shows the dent (deflection) of stainless steel pipe SP at the time of the predetermined space | interval of the grip ring of the coupling type pipe joint which concerns on embodiment of this invention being 12.0 mm with an end elevation. It is explanatory drawing which shows that the dent (deflection) of the stainless steel pipe SP does not arise when the predetermined space | interval X of the grip ring of a coupling type pipe joint same as the above is 18.0 mm.

  Hereinafter, a coupling type pipe joint according to an embodiment of the present invention will be described with reference to the drawings.

<Coupling type pipe fitting>
The coupling type pipe joint according to the embodiment of the present invention will be described with reference to FIGS. A case will be described by way of example in which the abutting stainless steel pipes that are not subjected to secondary processing such as threading or grooving are connected to each other by the coupling-type pipe joint according to the present embodiment.

  FIG. 1 is a perspective view showing a coupling type pipe joint 1 according to an embodiment of the present invention. FIG. 2 is a front view of the coupling type pipe joint 1 as viewed in the pipe axis direction, and FIG. 3 is a right side view thereof. FIG. 4 is an end view taken along line AA of FIG. 2 showing the coupling type pipe joint 1.

  As shown in FIGS. 1-4, the coupling type pipe joint 1 which concerns on embodiment of this invention is provided with the casing 2 which is a coupling main body. In this coupling type pipe joint 1, the casing 2 is externally fitted across the butted ends of two stainless steel pipes and is tightened by a fastening means 20 described later to connect these pipe ends. It is a coupling type pipe joint.

  As shown in FIG. 4, the casing 2 includes four grip rings 3 (3-1, 3-2), 3 ′ (3′- 1, 3 ′). -2) and a cylindrical rubber sleeve 4 interposed in these grip rings.

  Further, as shown in FIG. 4, a triangular ring 5 having a triangular cross section is provided on the inner side of the base end portion (portion on the casing 2 side) of the two inner grip rings 3-1 and 3′-1. It has been. In addition, a guide ring 6 is interposed between the inner grip rings 3-1 and 3'-1 and the outer grip rings 3-2 and 3'-2.

  As shown in FIG. 2, a protection ring 7 is provided inside the notched portions of the inner grip rings 3-1 and 3 ′-1, and the casing 2 and the rubber sleeve 4 are connected to each other. A slide plate 8 is interposed between them.

(casing)
The casing 2 is a member obtained by bending a stainless steel plate (SUS304) having a thickness of 2 mm into a C-shaped cross section and rolling the C-shaped steel material into a cylindrical shape having a slit-shaped opening 2a. (See FIG. 1 etc.). The casing 2 has a function as a housing of the coupling type pipe joint 1 as a whole.

  In addition, as shown in FIGS. 1 and 2, the casing 2 has a pair of tightening means accommodating portions, in which a part of the steel material in contact with the slit-shaped opening 2 a is folded back and secured in a bag shape. 2b is formed. The casing 2 is configured to reduce the diameter by tightening the slit-shaped opening 2a with the tightening means 20, tighten the attached stainless steel pipe, and connect the pipe ends.

(Tightening means)
In the present embodiment, the tightening means 20 includes three hexagon socket head bolts M12 made of stainless steel (SUSXM7). Further, the tightening means 20 includes one hole bar 22 that is a rod washer made of stainless steel (SUS304) and one soled bar 23 that is a rod nut made of stainless steel (SUS304).

  As shown in FIGS. 1 and 3, three fastening holes 2c for inserting hexagon socket head bolts 21 are formed in the tightening means accommodating portion 2b, and the hexagon socket head bolts 21 are inserted into the elongated holes 2c. It is inserted. Further, these hexagon socket head cap bolts 21 are screwed to the sored bar 23 through a hole bar 22 having three through holes.

(Grip ring)
Next, the grip ring 3 of the coupling type pipe joint 1 according to the present embodiment will be described with reference to FIG. FIG. 5 is a perspective view showing the grip ring 3 of the coupling type pipe joint 1.

  The grip ring 3 is made of a stainless steel plate (SUS301) having a thickness relatively higher than that of a stainless steel pipe to be connected and having a thickness of about 1 mm. As shown in FIG. 5, the grip ring 3 is a ring that is C-shaped when viewed in the tube axis direction in which a notch 3 a in which a part of the ring shape is notched so as to reduce the diameter is formed. is there.

  In addition, the grip ring 3 is formed with a cutting edge 3b in which a large number of cuts are formed so as to bite into a hard stainless steel pipe, and as shown in FIG. It is installed with an inclination of 45 degrees in the direction of falling inward with respect to the outer peripheral surface. For this reason, when the grip ring 3 bites into the steel pipe, a desired grip force can be exerted against the force with which the pipe is pulled out.

  In the present invention, it is one of the features that these two grip rings 3 are arranged in parallel with a predetermined distance X between each pair. Although the predetermined interval X will be described in detail later, it is required to be 12.0 mm or more, and preferably 18.0 mm or more. Although there is no theoretical upper limit value for the predetermined interval X, it is considered that 18.0 mm is optimal for the predetermined interval X because the casing 2 that accommodates these becomes too large and heavy.

(Rubber sleeve)
Next, the rubber sleeve 4 of the coupling type pipe joint 1 according to the present embodiment will be described with reference to FIG. FIG. 6 is a partial cross-sectional perspective view showing a state in which a part of the rubber sleeve 4 of the coupling-type pipe joint 1 is cut along the pipe axis direction. In the illustrated embodiment, the rubber sleeve 4 is shown in a cut state in order to show a special cross-sectional shape of the rubber sleeve 4, but the rubber sleeve 4 is a cylindrical member having no notch such as a slit.

  In this embodiment, the rubber sleeve 4 is a generally cylindrical sleeve made of synthetic rubber, and has a function of sealing so that the fluid flowing in the pipe of the pipe to be connected does not leak from the joint portion. . Of course, the rubber sleeve according to the present invention must be a substance that exhibits a rubber elasticity that undergoes a large elastic deformation with a small force and immediately returns to its original state when the force does not work.

  As shown in FIG. 6, the rubber sleeve 4 is folded at both ends in a cross section cut along the tube axis direction to form a folded portion 4a, and a groove portion 4b is formed inside thereof. In addition, a spring 41 that is an annular (ring-shaped) stainless steel (SUS316) coil spring is mounted in the groove 4b. For this reason, the adhesiveness (adhesion force) to the pipe | tube of the folding | returning part 4a which is the both ends of the rubber sleeve 4 increases, and the sealing force is improving.

  Then, three chevron-shaped chevron ribs 4c are formed in the inner part of the folded part 4a, and the rigidity of the central part on the thin cross section is improved without the folded part 4a, and the rubber sleeve 4 is twisted and cut. Can be prevented. Further, the formation of the chevron rib 4c increases the shape stability when the rubber sleeve 4 is brought into close contact with the tube, and the sealing force can be maintained even when a high pressure is applied in the tube. .

(Triangular ring)
Next, the triangular ring 5 of the coupling type pipe joint 1 according to the present embodiment will be described with reference to FIG. FIG. 7 is a perspective view showing the triangular ring 5 of the coupling type pipe joint 1.

  The triangular ring 5 is made of a stainless steel material (SUS301) having a triangular cross section (right isosceles triangular shape), and as shown in FIG. 7, a cutout portion 5a that is partially cut out so that the diameter can be reduced is formed. A C-shaped ring processed into a C-shape when viewed in the tube axis direction.

  As shown in FIG. 4, the triangular ring 5 is installed in a pair of left and right sides with the apex inside on the inner ends of the inner grip rings 3-1 and 3 ′-1 and the protection ring 7 described later. Yes. The triangular ring 5 has a function of supporting these grip rings 3-1 and 3'-1 with a 45 degree inclined surface of a right isosceles triangle and maintaining the inclination angle. Here, as shown in FIG. 4, the base end portion refers to an end portion on the casing 2 side that is the outside.

(Guide ring)
Next, the guide ring 6 of the coupling type pipe joint 1 according to the present embodiment will be described with reference to FIG. FIG. 8 is a perspective view showing the guide ring 6 of the coupling type pipe joint 1.

  The guide ring 6 is made of a stainless steel material having a trapezoidal cross section (SUS304), and as shown in FIG. 8, a notch 6a partly cut away so that the diameter can be reduced is formed. This is a C-shaped ring processed into a C-shape.

  As shown in FIG. 4, the guide ring 6 has a trapezoidal cross section on the inner side which is a vertical surface, and the outer side is an inclined surface having the same inclination as that of the triangular ring 5 described above. A pair of left and right guide rings 6 are provided on the base end side between the inner grip rings 3-1 and 3'-1 and the outer grip rings 3-2 and 3'-2. For this reason, the guide ring 6 functions as a spacer for maintaining a predetermined distance X between the grip rings 3 and the outer grip rings 3-2 and 3'-2 are inwardly inclined by the trapezoidal outer slope. It also has a function to maintain the tilt angle so that it will not fall over.

(Protection ring)
Next, the protection ring 7 of the coupling type pipe joint 1 according to the present embodiment will be described with reference to FIG. FIG. 9 is a perspective view showing the protection ring 7 of the coupling type pipe joint 1.

  The protection ring 7 is made of a flat stainless steel plate (SUS304), and as shown in FIG. 9, a cutout portion 7a is formed with a part cut away so that the diameter can be reduced. It is a C-shaped ring processed into a letter shape.

  As shown in FIG. 4, the protection ring 7 is interposed between the inner grip rings 3-1 and 3'-1 and the triangular ring 5, and the grip rings 3-1 and 3'-. 1 is provided at the notch 3a.

  The protection ring 7 has a function of preventing the rubber sleeve 4 from being pushed outward by the pressure in the pipe instead of the grip ring 3. For this reason, the protection ring 7 should just be mounted | worn with the notch part 3a part of the grip rings 3-1 and 3'-1. However, when it exists only in the notch part 3a part, there exists a possibility of dropping out or moving. Therefore, the protection ring 7 according to the present embodiment is a C-shaped C-shaped ring so as not to be fitted into the tube and fall off.

(slide plate)
Next, the slide plate 8 of the coupling type pipe joint 1 according to the present embodiment will be described with reference to FIGS.

  The slide plate 8 is made of a thin stainless steel plate (SUS301), and as shown in FIG. 4, edge portions 8a are formed by bending both ends in the tube axis direction so as to cover the outer peripheral surface of the rubber sleeve 4. .

  The slide plate 8 is bent into a circular arc shape (not shown) according to the curvature of the inner peripheral surface of the casing 2 from the stainless steel plate on which the edge portion 8a is formed. As shown in FIGS. 1 and 2, the slide plate 8 is mounted between the casing 2 and the rubber sleeve 4 so as to straddle the opening 2 a of the casing 2. The slide plate 8 is configured to slide on the inner peripheral surface of the casing 2 by being tightened by the tightening means 20 so that the opening 2a is contracted. The slide plate 8 covers and supports the outer peripheral surface of the rubber sleeve 4 in the opening 2 a of the casing 2, and has a function of preventing the rubber sleeve 4 from expanding due to pressure in the pipe.

  According to the coupling type pipe joint 1 which concerns on this embodiment demonstrated above, even if it is a case where stainless steel steel pipes are connected, the grip ring 3 bites into a stainless steel pipe without a thin stainless steel pipe bending. I can do it. For this reason, there is no need for secondary processing such as threading or grooving at the end of a stainless steel pipe that is difficult to machine, and it is possible to easily connect a stainless steel pipe and achieve a high pulling prevention force (grip force). it can.

  Moreover, according to the coupling type pipe joint 1, the guide ring 6 which maintains the space | interval of the inner side grip ring 3-1 (3'-1) and the outer side grip ring 3-2 (3'-2) of each pair. Is intervening. For this reason, the outer grip ring 3-2 (3′-2) is not displaced inward, and the outer grip ring 3-2 (3′-2) is not tilted and the inclination angle is not reduced. The ring 3 can be surely bitten into the stainless steel pipe.

  In addition, according to the coupling type pipe joint 1, the triangular ring 5 having a triangular cross section is provided to maintain the inclination angle of the inner grip ring 3-1 (3'-1). For this reason, it is possible to prevent the grip ring 3-1 (3'-1) from collapsing, and to make the grip ring 3 bite into the stainless steel pipe more reliably.

  Furthermore, according to the coupling type pipe joint 1, since the protection ring 7 is provided, it is possible to prevent the rubber sleeve 4 from being pushed outward by the pressure in the pipe. For this reason, the connection part of stainless steel pipes can be reliably sealed with the rubber sleeve 4, and there is no possibility that the fluid flowing in the pipe leaks out.

<Effect confirmation experiment>
Next, with reference to FIGS. 10 to 14 (see also FIGS. 1 to 9), an effect confirmation experiment will be described including the process up to the invention. In addition, the same structure as the above-mentioned coupling type pipe joint 1 attaches | subjects the same code | symbol, and omits detailed description.

  The inventors of the present invention have sought to develop a coupling type pipe joint that satisfies the joint performance standards of the Fire Service Act when connecting stainless steel pipes. However, the conventional coupling-type pipe joint 10 needs to increase the pull-out prevention force of the pipe (tensile strength in the pipe axis direction: grip force) that is far from the performance standard by about twice.

  10A and 10B are explanatory views showing the tightening state of the conventional coupling-type pipe joint 10 as an end view similar to FIG. 4, wherein FIG. 10A shows before tightening and FIG. 10B shows after tightening. . As shown in FIG. 10, the basic mechanism of the conventional coupling-type pipe joint 10 includes two hexagon socket head bolts 21 (not shown) which are fastening means 20 (not shown), and the grip ring 3 A pair of left and right was provided.

  In this conventional coupling-type pipe joint 10, when two hexagon socket head cap screws 21 are tightened, first, the casing 2, which is a coupling body, contracts in the circumferential direction, and the tip of the internal grip ring 3 is made of stainless steel. It contacts the surface of the steel pipe SP. Further, the tip is deeply bitten by increasing the torque value for turning the hexagon socket head bolt 21.

  Therefore, at first, the inventors considered to double the tightening force of the tightening means 20. Specifically, the number of hexagon socket head cap bolts 21 was increased from two to three (1.5 times), and the size of the hexagon socket head cap bolt 21 was increased from M10 to M12. This increases the effective cross-sectional area of the bolt by 1.4 times. For this reason, the axial force (allowable proof stress) of the whole fastening means 20 can be doubled or more.

  The initial assumption was that the penetration depth of the grip ring 3 into the stainless steel pipe doubled, and as a result, the tensile strength in the direction of the pipe axis was thought to improve significantly if not doubled. is there. However, as shown in FIG. 11, when a certain depth is reached, the steel pipe is dented or bent inwardly and elastically no matter how much the torque value (axial force) for turning the hexagon socket head bolt 21 is increased. It turns out that the biting depth does not increase by simply deforming. Of course, it did not lead to an increase in tensile strength (grip strength). FIG. 11 is an explanatory view showing in an end view that the steel pipe is recessed inward and does not reach the designed amount of bite, (a) shows the design state, and (b) shows the actual state. . In addition, 0.9 mm is the depth of penetration of the design grip ring 3 into the stainless steel pipe.

  FIG. 12 is an explanatory view showing, in an end view, a case where two pairs of grip rings 3 are mounted on a conventional coupling-type pipe joint 10. As shown in FIG. 12, the next idea was to mount two grip rings 3 in pairs. However, as a result, the stainless steel pipe SP is also dented inward, and the biting depth per sheet is reduced by 60% (0.9 mm → 0.5 mm), and the tensile strength (grip force) is also several. % Up stopped.

  FIG. 13 is an explanatory view showing a dent (deflection) of the stainless steel pipe SP in an end view when the predetermined interval X of the grip ring 3 of the coupling type pipe joint 1 according to the embodiment of the present invention is 12.0 mm. is there. As shown in FIG. 13, the next idea was to mount two pairs of grip rings 3 as in the above-described coupling type pipe joint 1 for the purpose of reducing the dents in the stainless steel pipe SP. At the same time, the predetermined interval X is set to 12.0 mm. Further, even if the guide ring 6, which is a hard ring having high hardness and is difficult to be deformed, is disposed between the grip rings 3, even if the tightening force (torque for turning the bolt) of the tightening means 20 is increased, a predetermined interval is provided. It was considered that X is held by the guide ring 6.

  As a result, the tensile strength (grip force) was improved by 30% compared to the conventional coupling-type pipe joint 10. However, the phenomenon in which the stainless steel pipe SP was recessed was not significantly different from the double stacking shown in FIG. Therefore, it can be said that if the predetermined distance X between the grip rings 3 arranged in parallel in each pair is 12.0 mm or more, a certain degree of improvement in tensile strength (grip force) can be expected.

  FIG. 14 is an explanatory view showing a dent (deflection) of the stainless steel pipe SP when the predetermined interval X of the grip ring 3 of the coupling-type pipe joint 1 according to the embodiment of the present invention is 18.0 mm. As shown in FIG. 14, next, the predetermined interval X of the grip ring 3 is gradually increased to 6.0 mm, 12.0 mm, and 18.0 mm, and the dent (deflection) of the stainless steel pipe SP is observed. At the same time, the tensile strength (grip force) was measured.

  As a result, when the predetermined interval X of the grip ring 3 was 6.0 mm, there was almost no change in the amount of dent in the stainless steel pipe SP, but in the case of 12.0 mm, the guide ring 6 By adopting the holding configuration, the tensile strength (grip force) was improved by 70% compared to the conventional coupling-type pipe joint 10. It was also observed that the amount of dent in the stainless steel pipe SP was reduced. Therefore, it is found that if the predetermined distance X between the grip rings 3 arranged in parallel in each pair is 12.0 mm or more, a preferable result that the tensile strength (grip force) is improved by 70% compared to the conventional case is achieved. It can be said that.

  Next, as shown in FIG. 14, the predetermined interval X between the grip rings 3 is set to 18.0 mm, and this is held by the guide ring 6. The experimental result in this case showed that the tensile strength (grip force) was increased to about twice that of the conventional coupling-type pipe joint 10 as expected. Moreover, the dent of the stainless steel pipe SP was hardly observed.

  Thus, even if the predetermined interval X is further increased, the tensile strength (grip force) and the dent of the stainless steel pipe SP are considered to be the same as when the predetermined interval X is 18.0 mm. In short, theoretically, the predetermined distance X between the grip rings 3 may be any amount as long as it is 18.0 mm or more. However, considering that it is easy to carry by human power, it is desirable that the coupling-type pipe joint 1 achieves weight reduction. Accordingly, it can be said that the predetermined interval X is optimally 18.0 mm.

  In addition, the coupling type pipe joint 1 according to the embodiment of the present invention has been described by exemplifying one provided with two left and right grip rings 3. However, in order to further improve the tensile strength (grip force), the grip ring 3 It is considered good to provide three pairs of left and right. Even in that case, it is necessary that the gaps between the grip rings 3 be at least a predetermined distance X.

  As described above, the coupling type pipe joint according to the embodiment of the present invention and the principle of the invention have been described in detail. However, each of the above-described or illustrated embodiments shows an embodiment embodied in carrying out the present invention. It is just a thing. Therefore, the technical scope of the present invention should not be limitedly interpreted by these.

  In particular, a stainless steel pipe has been exemplified and described as a metal pipe to be connected by a coupling-type pipe joint, but it goes without saying that the present invention can also be applied to the case where other metal pipes are connected. Since stainless steel pipes having high hardness and thin pipes can be connected to each other to achieve a desired gripping force, it is clear that various metal pipes having lower hardness can be connected to each other.

1: Coupling-type fitting 2: Casing (coupling body)
2a: Opening 2b: Tightening means accommodating portion 2c: Long hole 20: Tightening means 21: Hexagon socket head bolt (bolt)
22: Hall bar (bar washer)
23: Sored bar (bar nut)
3, 3 ': Grip ring 3-1, 3'-1: Inner grip ring (grip ring)
3-2, 3'-2: Outer grip ring (grip ring)
3a: Notch 3b: Cutting edge 4: Rubber sleeve 4a: Folded part 4b: Groove 4c: Angle rib 41: Annular spring (spring)
5: Triangular ring 5a: Notch portion 6: Guide ring 6a: Notch portion 7: Protection ring 7a: Notch portion 8: Slide plate 8a: Edge portion 10: Conventional coupling pipe joint SP: Stainless steel pipe

Claims (5)

It has a cylindrical coupling body that is formed with a slit along the tube axis direction and can be tightened by tightening means, and this coupling body is externally fitted across the ends of the two metal tubes that are abutted. A coupling type pipe joint for connecting these pipe ends,
The coupling body has a plurality of pairs of grip rings each having a ring-shaped part that is cut out so that the diameter thereof can be reduced and biting into the metal pipe, and a pair of grip rings that are relatively high in hardness. A cylindrical rubber sleeve for sealing a fluid in the pipe of the metal pipe to be connected,
The coupling type pipe joint, wherein the plurality of pairs of grip rings are provided in plural at each pipe end at a predetermined interval. The coupling type pipe joint according to claim 1, wherein a guide ring is provided between each pair of the grip rings so as to maintain a distance therebetween. 3. The triangular ring having a triangular cross section for holding the inclination angle of the grip ring is provided inside the base end portion of the grip ring inside each pair. 4. Coupling type pipe fitting. The protection ring for preventing the rubber sleeve from being pushed out by the pressure in the pipe is provided inside the notched portion of the grip ring inside each pair. The coupling type pipe joint according to any one of 1 to 3. The coupling-type pipe joint according to any one of claims 1 to 4, wherein an annular spring is attached to the rubber sleeve in the vicinity of both ends to enhance adhesion to the metal tube.

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