JP6523613B2 - Pipe fitting - Google Patents

Description

  The present invention relates to a pipe joint, and more particularly to a pipe joint referred to as a double ferrule type pipe joint or the like.

  A pipe joint called a double ferrule type pipe joint comprises a tubular body into which a pipe is inserted from the rear end side, a front ring and a buckling which are fitted around a pipe projecting from the rear end side of the body, and a front ring And a cap nut that clamps the buckling to fix the tube to the body, and is well known in the art (eg, Patent Document 1).

  In such a pipe joint, the buckling has a tapered surface which is recessed into the inner periphery of the front ring, and the inner peripheral surface of the front ring has a cylindrical surface and a tapered surface connected to the rear end of the cylindrical surface. doing. The tapered surface of the front ring has a taper angle that is equal to or approximately equal to the tapered surface of the buckling.

  When the cap nut is tightened, the front end portions of the front ring and the back ring are deformed radially inward to bite into the pipe and the pipe is strongly tightened. As a result, the required pipe holding power can be obtained, and a pipe joint having sufficient sealability even in a high pressure environment can be obtained.

Japanese Patent Publication No. 2010-534804

  In this type of pipe joint, reduction in tightening torque is required. However, when the tightening torque is reduced, the pipe holding force is reduced, and there is a problem that the reduction of the tightening torque is difficult.

  An object of the present invention is to provide a pipe joint capable of reducing a tightening torque.

The pipe joint according to the present invention comprises a tubular body into which a pipe is inserted from the rear end side, a front ring and a buckling which are fitted around a pipe projecting from the rear end side of the body, and a pipe by tightening the front ring and the buckling. And a cap nut for fixing the body to the body, and the back ring has a tapered surface which is recessed into the inner periphery of the front ring, and the inner periphery of the front ring is a cylindrical surface and a tapered surface connected to the rear end of the cylindrical surface The tapered surface of the front ring is between the rear tapered surface having a taper angle corresponding to the tapered surface of the back ring and the rear tapered surface and the cylindrical surface, of Ri Do from a front tapered surface having a smaller taper angle than the taper angle relates axial length, the axial direction of the axial of the rear tapered surface length of the front tapered surface length It is characterized in greater than.

  At the time of tightening, the front ring and the buckling are advanced while the tapered surface of the buckling penetrates into the tapered surface of the front ring. Along with this, the front end portions of the front ring and the buckling are deformed radially inward to bite into the pipe. Here, the tapered surface of the front ring is conventionally a single-step tapered surface, but this is the two-step tapered surface on the rear side and the front side. Thus, in the first half of tightening, the contact surface of the tapered surface of the front ring with the tapered surface of the buckling is the rear tapered surface, and both tapered surfaces have a relatively large taper angle. , The required tube holding power is ensured. In the second half of the tightening, the contact surface of the tapered surface of the front ring with the tapered surface of the back ring shifts from the rear tapered surface to the front tapered surface, which makes it easy for the buckling to dig into the front ring. Therefore, the increase in torque in the second half of tightening is mitigated. Thus, the tightening torque can be reduced after securing the required pipe holding power.

  According to the present invention, in the first half of tightening, the contact surface with the tapered surface of the back ring on the tapered surface of the front ring is made to be the rear tapered surface, and the required tube holding power is secured, and In the latter half of the tightening, the contact surface of the tapered surface of the front ring with the tapered surface of the back ring shifts to the front tapered surface, so that the back ring can easily dig into the front ring. Therefore, the increase in torque in the second half of tightening is mitigated, and thus the tightening torque can be reduced while securing the required pipe holding force.

FIG. 1 is a longitudinal sectional view showing an assembled state of an embodiment of a pipe joint according to the present invention. FIG. 2 is a longitudinal sectional view showing the front ring and the buckling of FIG. 1 in an enlarged manner. FIG. 3 is a longitudinal sectional view showing the front ring and the buckling of FIG. 2 separately. FIG. 4 is a diagram comparing the tightening state of the conventional pipe joint and that of the embodiment. FIG. 5: is a figure which compares transition of the fastening torque with the conventional pipe joint and the thing of embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

  In this specification, with regard to the context, the left side of FIG. 1 is referred to as the front, and the right side is referred to as the rear with reference to FIG.

  As shown in FIG. 1, the pipe joint (30) of the present invention has a tubular body (joint member) (31) into which a pipe (32) is inserted from the rear end side and a projection from the rear end side of the body (31). Ring for fastening the tube (32) to the body (31) by tightening the front ring (33) and the buckling (34) fitted around the broken tube (32) and the front ring (33) and the buckling (34) It has a nut (35).

  An outward facing flange (36) is formed on the outer periphery of the middle portion of the body (31), and screw portions (37) and (38) are formed on the outer peripheries of the front and rear ends thereof. A large diameter portion (31a) having a slightly larger inner diameter than the front portion is formed on the inner periphery of the rear end of the body (31), and a tapered surface (the diameter decreases toward the front) on the inner periphery of the rear end. 31b) is formed.

  An internal thread (35a) is formed on the inner periphery of the front end portion side of the cap nut (35), and this is screwed onto the external thread portion (38) of the rear end portion of the body (31). An inward flange (35b) is formed at the rear end of the cap nut (35).

  The front ring (33) and the buckling (34) are shown enlarged in FIGS. The pipe joint (30) of the present invention is characterized by the shape of the front ring (33), which will be described in detail with reference to FIGS. 2 and 3.

  A tapered surface (40) that matches the tapered surface (31b) at the rear end of the body (31) is formed on the outer periphery of the front ring (33). The inner periphery of the front ring (33) has a cylindrical surface (41) and a tapered surface (42) connected to the rear end of the cylindrical surface (41). An annular groove (43) having a triangular cross-section is formed in the front part of the cylindrical surface (41) on the inner periphery of the front ring (33). Further, an annular groove (44) having a rectangular cross section is formed at the front end of the cylindrical surface (41).

The tapered surface (42) of the front ring (33) is a two-step tapered surface consisting of a rear tapered surface (42a) and a front tapered surface (42b). Both the rear side tapered surface (42a) and the front side tapered surface (42b) are tapered surfaces whose diameters become smaller as they go forward. As can be seen from FIG. 3, regarding the axial length, the axial length of the front tapered surface (42b) is made larger than the axial length of the rear tapered surface (42a).

  The front end of the back ring (34) is formed with a tapered surface (45) whose diameter decreases as it goes forward into the tapered surface (42) of the front ring (33).

  In the above, the taper angle α of the tapered surface (45) of the buckling (34) is 88 ° (44 ° as the angle with the axis), and the taper of the rear tapered surface (42a) of the front ring (33) The angle β is 90 ° (45 ° as the angle with the axis), and the taper angle γ of the front tapered surface (42b) of the front ring (33) is 45 ° (22.5 as the angle with the axis) ).

  In the pipe joint (30), when the cap nut (35) is tightened, the front face of the inward flange (35b) of the cap nut (35) contacts the back face of the buckling (34) and advances it. When the tapered surface (40) on the outer periphery of the front ring (33) abuts on the tapered surface (31b) at the rear end of the body (31), the resistance to tightening starts to increase, further tightening the cap nut (35) , And the front ring (33) and the buckling (34), while the tapered surface (40) of the outer periphery of the front ring (33) digs into the tapered surface (31b) of the body (31), and the buckling (34) The tapered surface (45) is advanced while intruding into the tapered surface (42) of the front ring (33). As a result, the front end portions of the front ring (33) and the buckling (34) are deformed radially inward and bite into the pipe (32). As the amount of biting in increases, the pipe holding force increases, the resistance to tightening also increases, and the tightening torque increases.

  In the first half of tightening, the contact surface of the tapered surface (42) of the front ring (33) with the tapered surface (45) of the buckling (34) is the rear tapered surface (42a). The relatively large taper angle of (42a) ensures the required tube retention. In the latter half of tightening, the contact surface of the tapered surface (42) of the front ring (33) with the tapered surface (45) of the buckling (34) shifts from the rear tapered surface (42a) to the front tapered surface (42b) This makes it easier for the buckling (34) to slip into the front ring (33). Therefore, the increase in torque in the second half of tightening is mitigated. Thus, the tightening torque can be reduced after securing the required pipe holding power.

  In FIG. 4, the conventional pipe joint (the tapered surface (40) of the front ring (33 ') is one step) (FIG. 4 (a)) and the taper of the pipe joint (front ring (33) of the above embodiment) The plane (40) shows two stages (30) (FIG. 4 (b)).

  In FIG. 4, the two do not differ until the cap nut (35) rotates 3⁄4 (not shown), but the cap nut (35) exceeds 1 rotation, and 1 and 1⁄4 of the specified number of rotations. When the rotation is reached, in the present embodiment shown in FIG. 4 (b), the contact between the boundary between the back tapered surface (42a) and the front tapered surface (42b) of the front ring (33) and the buckling (34) The stress on the surface increases, and the buckling (34) sinks more under the front ring (33) than the conventional one shown in FIG. 4 (a), and the front ring (33) bounces slightly upward. ing.

  In the case of FIG. 4 (b), since the buckling (34) indents more under the front ring (33), the buckling (34) of the same size as that of FIG. Since the space between the ring (33) and the buckling (34) does not occur and the effect of retightening can not be obtained, the dimension of the buckling is also changed.

  FIG. 5 shows that the conventional pipe joint (the tapered surface (40) of the front ring (33 ') is one step) and the pipe joint (front ring (33)) of the above embodiment have two steps It is the graph which compared transition of tightening torque about (30).

  In FIG. 5, the tightening torques of the conventional pipe joint and the pipe joint of the above embodiment are measured for a steel pipe having a diameter of 6.35 mm and a wall thickness of 0.89 mm. Compared with the conventional product, it is 49% lower from 21.3 N · m to 10.9 N · m on average at 10 locations.

  Thus, the tightening torque can be reduced while securing the necessary bite force (pipe holding force).

  Here, the above effect can be obtained by making the taper angle γ of the front side tapered surface (42b) of the front ring (33) smaller than the taper angle β of the rear side tapered surface (42a) of the front ring (33). it can.

  As a preferable range of each taper angle, as an example, the taper angle α of the taper surface (45) of the buckling (34) is 80 to 120 °, and the taper angle β of the rear taper surface (42a) of the front ring (33) And the taper angle of the front tapered surface (42b) of the front ring (33) is 30 to 60 °.

  (30): Pipe fitting, (31): Body, (32): Pipe, (33): Front ring, (34): Back ring, (35): Cap nut, (41): Cylindrical surface, (42) : Tapered surface, (42a): Rear tapered surface, (42b): Front tapered surface, (45): Tapered surface

Claims (2)

A tubular body into which a pipe is inserted from the rear end side, a front ring and a buckling fitted around the pipe protruding from the rear end side of the body, and a cap nut for clamping the front ring and the buckling to fix the pipe to the body A tube joint having a tapered surface in which the buckling is recessed into the inner periphery of the front ring, and the inner periphery of the front ring having a cylindrical surface and a tapered surface connected to the rear end of the cylindrical surface In
The taper surface of the front ring is between the rear side taper surface having a taper angle corresponding to the taper surface of the back ring and the rear side taper surface and the cylindrical surface, and the taper angle smaller than the taper angle of the rear side taper surface Ri Do from the front tapered surface having,
A pipe joint characterized in that the axial length of the front tapered surface is larger than the axial length of the rear tapered surface with respect to the axial length .   The taper angle of the tapered surface of the buckling is 80 to 120 °, the taper angle of the rear tapered surface of the front ring is 80 to 120 °, and the taper angle of the front tapered surface of the front ring is 30 to 60 The pipe joint according to claim 1, characterized in that it is in degrees.