JP2008190613A - Joint part structure of hydraulic piping - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint part structure of hydraulic piping having excellent liquid-tightness and enabling working efficiency and working load on a worker to be reduced. <P>SOLUTION: This joint part structure of hydraulic piping comprises a collet 11 in which a truncated cone part 13 having a seal surface 14 formed on the outer peripheral surface and a communication hole 18 are formed at the bottom 12c of a female screw hole 12 and a flare nut 21 rotatably fitted to a flare pipe 2 and having a male screw part 23 in which a pressing part 24 in contact with the flare part 3 is formed at the end. A ring groove is formed in the inner peripheral surface of the communication hole. The rigidity of the truncated cone part 13 is reduced by the ring groove 19, and the inner peripheral surface 3a of the flare part 3 is sealingly pressed against the seal surface 14 with a uniform pressing force. Therefore, the liquid-tightness therebetween can be ensured. Consequently, the tightening torque of the flare nut 21 can be reduced, the working efficiency can be enhanced, and the working load on the worker can be remarkably reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a joint part structure of a hydraulic pipe such as a brake pipe used for a vehicle or the like.

  A hydraulic pipe of a vehicle, for example, a brake pipe, is generally configured by combining a steel pipe and a flexible hose made of rubber or the like used for a portion having a relative displacement in the pipe. For example, a flare pipe joint disclosed in Patent Document 1 is used at the joint between the steel pipe and the hose.

  The flare pipe joint shown in Patent Document 1 will be described with reference to FIG. Fig.7 (a) shows the decomposition | disassembly state of the flare pipe coupling 100, FIG.7 (b) has shown the combined state.

  The flare pipe joint 100 includes a collet 101 to which a flexible hose 121 is connected and a flare nut 111 to which a steel pipe, so-called flare pipe 122 is connected.

  As shown in FIG. 7A, the collet 101 has a female screw hole 102 and a conical taper-shaped sealing surface 103 formed on one side, a hose insertion tube 104 and a hose receiving port 105 formed on the other side, and an outer periphery. The outward flange portion 106 is integrally formed. The outward flange portion 106 is formed in a polygon that can be engaged with a tightening tool such as a torque wrench, for example, a hexagon.

  The female screw hole 102 includes an opening-side screw hole portion 102a and a bottom-side inner hole portion 102b. The conical taper is gradually reduced in diameter toward the opening side from the bottom portion 102c side to the bottom portion 102c of the female screw hole 102. A planar sealing surface 103 is formed. The hose insertion tube 104 is formed in a tubular shape with an open end, and the hose receiving port 105 is formed in a tubular shape that surrounds the outer periphery of the hose insertion tube 104 with a gap.

  The seal surface 103 is formed on a coaxial core with a communication hole 107 communicating the female screw hole 102 and the hose insertion tube 104 as a center. The outer peripheral shape of the seal surface 103 is similar to the shape of the inner peripheral surface 123 a of the flare portion 123 formed at the tip of the flare tube 122, and the communication hole 107 opens at the top of the seal surface 103. The tip 121a of the hose 121 is fitted and inserted into the hose insertion pipe 104, and is crimped and joined from the outside by the hose receiving port 105.

  On the other hand, the flare nut 111 includes a pressure contact portion 114 at the tip of a cylindrical male screw portion 113 having a through hole 112 and an outward flange portion 115. The male screw portion 113 is configured to be screwed into the screw hole portion 102a of the collet 101 so as to advance and retreat, and the press contact portion 114 is formed in a conical taper surface shape whose diameter is gradually increased as it moves to the tip side. . Further, the inner diameter of the through hole 112 is formed such that the flare tube 122 can be fitted, and is smaller than the outer diameter of the flare portion 123. Further, the outward flange portion 115 is formed in a polygon that can be engaged with a tightening tool such as a torque wrench, for example, a hexagon.

  In the flare pipe joint 100 configured as described above, when the flare nut 111 is rotatably fitted to the flare pipe 122 and screwed into the screw hole portion 102a of the female screw portion 102 of the collet 101, tightening is performed. As shown in (b), the pressure contact portion 114 of the flare nut 111 abuts on the flare portion 123 of the flare tube 112 to press the flare portion 123 against the seal surface 103 of the collet 101, and the flare portion 123 is liquid-tightly sealed. 103.

Japanese Patent Laid-Open No. 7-12274

  According to the joint structure of the hydraulic piping using the flare pipe joint 100 disclosed in Patent Document 1, the male threaded portion 112 of the collet 101 to which the hose 121 is connected in a state where the flare pipe 122 is fitted to the flare nut 111. Thus, the flare tube 122 and the hose 121 can be connected to each other by the fluid-tight pressure contact of the flare portion 123 of the flare tube 122 with the seal surface 103 of the collet 101.

  However, according to the flare pipe joint 100, the male threaded portion 112 of the flare nut 111 is screwed into the screw hole portion 102 a of the collet 101 and tightened to tighten the flare tube 122 through the pressure contact portion 114 in the axial direction. Since the inner peripheral surface 123a of the flare part 123 is pressed against the seal surface 103 and sealed in a liquid-tight manner, the thickness t of the flare part 123 is partially formed unevenly. If there is a dimensional error in the flare portion 123, the inner peripheral surface 123a of the flare portion 123 is in a single-contact state with the seal surface 103 of the collet 101, and the pressure contact force of the flare portion 123 with respect to the seal surface 103 is increased and unstable. It may become a state and liquid tightness may be impaired.

  As a countermeasure, the flare portion 123 is sealed through the pressure contact portion 113 of the flare nut 111 with a large axial pressing force by tightening the male screw portion 112 of the flare nut 111 to the screw hole portion 102a of the collet 101 with a larger tightening torque. There is a method of ensuring liquid-tightness by pressing with a large pressing force against the surface 103. However, since the flare nut 111 is tightened with a large tightening torque, the work efficiency is greatly lowered and the work load on the worker is increased. In addition, when the tightening torque is excessively large, the flare 123 and the seal surface 103 are deformed by the action of a large pressing force, and the liquid-tight sealability between the flare 123 and the seal surface 103 may be impaired. Concerned.

  Accordingly, an object of the present invention made in view of such a point is to provide a joint part structure of a hydraulic pipe that is excellent in liquid tightness and can be expected to reduce work efficiency and reduce the work load of an operator.

  The invention of the joint part structure of the hydraulic pipe according to claim 1, which achieves the above object, is formed so as to protrude from the bottom of the female screw hole whose one end is open and transition to the opening side, so that the outer peripheral surface is gradually reduced in diameter. A collet having a trapezoidal portion and a communication hole opening at the top end of the frustoconical portion, and a conical taper-shaped sealing surface formed on the outer peripheral surface of the frustoconical portion, and a flare having a flare portion at the tip A flare nut having a male threaded portion that is fitted to a tube so as to be rotatable and has a pressure contact portion that abuts on the flare portion at the tip and is screwed into the female screw hole. The male threaded portion of the flare nut In the joint structure of the hydraulic piping that connects the flare pipe and the collet by pressing the inner peripheral surface of the flare part to the seal surface by screwing and tightening to the female screw hole of the collet, the bottom of the female screw hole When And characterized by forming an annular groove continuous in the circumferential direction on the inner peripheral surface of the communicating hole in the axial direction range corresponding to between the top end of the frustum-shaped portion.

  According to the present invention, the flare nut is threaded into the collet screw hole and tightened to apply axial pressure to the flare tube through the pressure contact portion of the flare nut. Even if there is a dimensional error in the flare part of the flare tube, the inner peripheral surface of the part is pressed against the seal surface formed in the truncated cone shape whose rigidity is suppressed by the annular groove with deformation of the seal surface. A good sealing state can be obtained with a uniform pressure contact force between the inner peripheral surface of the flare portion and the sealing surface.

  Also, the rigidity of the frustoconical part is suppressed by the annular groove, and the sealing surface and the inner peripheral surface of the flare part are pressed and sealed with deformation, so the pressure contact force of the flare part against the sealing surface during tightening is reduced. It is possible to reduce the tightening torque of the flare nut, and the work efficiency is improved and the work load on the worker is greatly reduced.

  According to a second aspect of the present invention, in the joint structure of the hydraulic piping according to the first aspect, the annular groove is formed within a plastic deformation range of the frustoconical portion generated by the flared portion being pressed against the seal surface. It is characterized by that.

  According to the present invention, the annular groove can be effectively sealed in a liquid-tight manner by forming it in a range where plastic deformation is possible.

  The invention according to claim 3 is formed at the bottom of the female screw hole whose one end is open and is shifted to the opening side, so that the outer peripheral surface is gradually reduced in diameter, and the top of the frustoconical portion is opened. And a collet having a conical tapered surface formed on the outer peripheral surface of the frustoconical portion, and a flare tube having a flare portion at the tip portion, and rotatably fitted to the tip. The flare nut is formed with a pressure contact portion that contacts the flare portion and has a male screw portion that is screwed into the female screw hole. The male screw portion of the flare nut is screwed into the female screw hole of the collet and tightened. Accordingly, in the joint structure of the hydraulic piping that connects the flare pipe and the collet by pressing the inner peripheral surface of the flare portion to the seal surface by the press contact portion, the seal surface extends in the circumferential direction of the flare portion. Line contact on inner surface Characterized in that the formation of the that annular projection.

  According to the present invention, when an axial pressing force is applied to the flare portion of the flare pipe through the pressure contact portion of the flare nut by screwing and tightening the male screw portion of the flare nut into the screw hole portion of the collet, the flare portion The inner circumferential surface of the annular projection is pressed against the annular projection in a line contact state, and the annular projection is pressed against the annular projection while being plastically deformed to be sealed in a liquid-tight manner.

  In addition, since the annular protrusion formed on the seal surface is sealed by being plastically deformed and the inner peripheral surface of the flare portion is pressed and sealed in an annular line contact state, the pressure contact force on the collet seal surface of the flare portion is reduced. It is possible to reduce the tightening torque of the flare nut, and the work efficiency is improved and the work load on the worker is greatly reduced.

  According to a fourth aspect of the present invention, in the joint structure of the hydraulic pipe according to the third aspect, the annular protrusion is a flare portion when an axial pressing force is applied to the flare portion of the flare pipe by the pressure contact portion of the flare nut. It is formed in the range which contact | abuts to the internal peripheral surface of this at the initial stage.

  According to the present invention, the annular protrusion is formed in a range where the annular protrusion comes into contact with the inner peripheral surface of the flare portion at an initial stage, so that it is possible to effectively impart plastic deformation to the annular protrusion and the liquid-tight sealing is achieved.

  The invention according to claim 5 is a truncated cone-shaped portion that protrudes from the bottom of the female screw hole that opens at one end and moves toward the opening side, and thus the outer peripheral surface is gradually reduced in diameter, and opens at the top end of the truncated cone-shaped portion. And a collet having a conical tapered surface formed on the outer peripheral surface of the frustoconical portion, and a flare tube having a flare portion at the tip portion, and rotatably fitted to the tip. The flare nut is formed with a pressure contact portion that contacts the flare portion and has a male screw portion that is screwed into the female screw hole. The male screw portion of the flare nut is screwed into the female screw hole of the collet and tightened. Thus, in the joint structure of the hydraulic piping that connects the flare pipe and the collet by pressing the inner peripheral surface of the flare portion to the seal surface by the press contact portion, the inner peripheral surface of the flare portion extends in the circumferential direction. Seal of the above collet Characterized in that the formation of the annular projection of line contact with.

  According to a sixth aspect of the present invention, in the joint part structure of the hydraulic circuit according to the fifth aspect, the annular projection is formed when the axial pressing force is applied to the flare portion of the flare pipe by the pressure contact portion of the flare nut. It is characterized in that it is formed in a range where it abuts on the sealing surface in the initial stage.

  According to the present invention, by forming the annular protrusion in a range where it comes into contact with the sealing surface of the collet at an initial stage, it is possible to effectively impart plastic deformation to the annular protrusion, and the liquid-tight sealing is performed.

  According to this invention, by applying the axial pressing force to the flare part of the flare tube through the pressure contact part of the flare nut by screwing the male thread part of the flare nut into the screw hole part of the collet and tightening, The liquid tightness is not impaired and a good sealing state is obtained.

  In addition, it is possible to reduce the pressing force of the flare part against the seal surface of the collet during tightening, and it is possible to reduce the tightening torque of the flare nut, improving work efficiency and greatly reducing the work load on the operator. Is done.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a joint structure of a hydraulic pipe according to the present invention will be described with reference to the drawings.

(First embodiment)
The first embodiment will be described with reference to FIGS. 1A is a sectional view showing an exploded state of a joint portion of a hydraulic pipe 1 such as a brake pipe of a vehicle, for example. FIG. 1B is an enlarged view of a portion A of FIG. Sectional drawing of the joint part which shows a coupling | bonding state, the same figure (b) is the B section enlarged view of (a).

  The hydraulic pipe 1 is configured by combining a steel pipe, that is, a flare pipe 2 and a flexible hose 5 made of rubber or the like used for a portion having relative displacement, and a joint portion between the flare pipe 2 and the hose 5 A flare fitting 10 is used.

  The flare pipe joint 10 includes a collet 11 to which the hose 5 is connected and a flare nut 21 to which the flare pipe 2 is connected.

  The collet 11 is formed of a machined metal material, for example, iron, stainless steel, aluminum, brass or copper. As shown in FIG. 1, a female screw hole 12 and a truncated cone part 13 are formed on one side, and a hose is inserted on the other side. The tube 15 and the hose receiving port 16 are integrally formed, and an outward flange portion 17 is formed to protrude from the outer periphery. The outward flange portion 17 is formed in a polygon that can be engaged with a tightening tool such as a torque wrench, for example, a hexagon.

  The female screw hole 12 includes a screw hole portion 12a on the opening side and an inner hole portion 12b on the bottom side, and the outer peripheral surface is gradually reduced in diameter toward the bottom portion 12c of the female screw hole 12 from the bottom portion 12c side to the opening side. A frustoconical portion 13 is formed so as to protrude, and a conical taper-like sealing surface 14 is formed on the outer peripheral surface of the frustoconical portion 13 so as to gradually decrease in diameter as it moves from the bottom 12c side to the opening side. The hose insertion tube 15 is formed in a tubular shape with an open end, and the hose receiving port 16 is formed in a tubular shape surrounding the outer periphery of the hose insertion tube 15 with a gap.

  The circular trapezoidal portion 13 is formed on the coaxial core with the communication hole 18 communicating the female screw hole 12 and the hose insertion tube 15 as the center, and the sealing surface 14 is the flare portion 3 formed at the tip of the flare tube 2. The shape is similar to the shape of the inner peripheral surface 3 a, and the communication hole 18 opens at the top end portion 13 a of the frustoconical portion 13. The tip 6 of the hose 5 is fitted into the hose insertion tube 15 and is crimped from the outside by a hose receiving port 16.

  Further, an annular groove 19 having a semicircular cross section that is continuous in the circumferential direction is formed on the inner peripheral surface 18a of the communication hole 18 along the top end portion 13a of the truncated cone portion 13. This annular groove 19 is within the axial range of the communication hole 18 corresponding to the frustoconical portion 13, more specifically, the shaft of the frustoconical portion 13 that can be plasticized by the pressure contact force of the flare portion 3 by tightening the flare nut 21 described later. It is formed within the range of directions. By this annular groove 19, the frustoconical portion 13 is formed to be relatively soft by suppressing the rigidity against the axial load at the tip portion.

  The flare nut 21 is formed of a machined metal material, for example, iron, stainless steel, aluminum, brass, or copper. As shown in FIG. 1, the pressure contact portion 24 is attached to the tip of a cylindrical male screw portion 23 having a through hole 22. And an outward flange portion 25 at the proximal end. The outward flange 25 is formed in a polygon that can be engaged with a tightening tool such as a torque wrench, for example, a hexagon.

  The male screw portion 23 is configured to be screwed into the screw hole portion 12a of the collet 11 so as to advance and retreat, and the press contact portion 24 is formed in a conical taper surface shape that gradually increases in diameter as it moves to the tip side. . Further, the through hole 22 of the flare nut 21 is formed with an inner diameter that allows the flare tube 2 to be rotatably inserted and formed smaller than the outer diameter of the flare portion 3.

  The flare tube 2 is formed of a metal material such as iron, stainless steel, aluminum, brass, or copper, and has an outer diameter that fits into the through hole 22 of the flare nut 21 as shown in FIG. A conical taper-shaped flare portion 3 is formed which gradually increases in diameter as it moves to the tip side. Further, the inner peripheral surface 3 a of the flare portion 3 is formed in a shape similar to the shape of the seal surface 14 of the collet 11.

  In the flare pipe joint 10 thus configured, the male thread portion 23 of the flare nut 21 is screwed into the screw of the collet 11 with the flare pipe 2 fitted in the through hole 22 of the flare nut 21 as shown in FIG. By screwing and tightening into the hole 12a, an axial pressing force is applied to the flare part 3 of the flare tube 2 by the pressure contact part 24 of the flare nut 21, and the inner periphery of the flare part 3 is applied to the seal surface 14 of the collet 11. The surface 3a is brought into contact.

  Further, when the flare nut 21 is tightened, an axial pressing force that presses the inner peripheral surface 3 a of the flare portion 3 against the seal surface 14 is applied to the flare portion 3 of the flare tube 2 by the press contact portion 24 of the flare nut 21. While being in pressure contact with the seal surface 14 of the collet 11, the annular groove 19 is formed relatively soft according to the uneven strength of the pressure contact force generated due to the dimensional error of the partial thickness t of the flare portion 3. As shown in FIG. 2, the frustoconical part 13 is crushed and plastically deformed, so that the sealing surface 14 and the inner peripheral surface 3a of the flare part 3 are in pressure contact with each other with a uniform pressing force over the entire circumference.

  According to the joint part structure configured as described above, the male thread part 23 of the flare nut 21 is screwed into the screw hole part 12a of the collet 11 and tightened to tighten the flare pipe 2 via the pressure contact part 24 of the flare nut 21. An axial pressing force is applied to the flare portion 3 so that the inner peripheral surface 3a of the flare portion 3 is in pressure contact with the seal surface 14 and is pressed and liquid-tightly sealed while applying plastic deformation to the seal surface 14. Even when there is a dimensional error in the flare 3 such that the thickness t of the flare 3 of the flare tube 2 is partially uneven, the inner peripheral surface 3a of the flare 3 is uniformly pressed against the seal surface 14. A good sealing state can be obtained without a loss of liquid tightness due to a force sealing state.

  Further, the frustoconical portion 13 is formed by the annular groove 19 to have low rigidity, and the seal surface 14 and the inner peripheral surface 3a of the flare portion 3 are pressed and sealed together with plastic deformation. The pressure contact force of the collet 11 with respect to the seal surface 14 can be reduced, the tightening torque of the flare nut 21 can be reduced, the work efficiency is improved, and the work load on the operator is greatly reduced. Furthermore, the dimensional accuracy required for the flare portion 3 of the frame tube 2 can be relaxed, and reduction in productivity and manufacturing cost can be expected.

(Second Embodiment)
A second embodiment will be described with reference to FIGS. 3 and FIG. 4, the same reference numerals are given to the portions corresponding to those in FIG. 1 and FIG.

  3A is a cross-sectional view showing an exploded state of a joint portion of a hydraulic pipe 1 such as a brake pipe of a vehicle, for example, FIG. 3B is an enlarged view of a portion C of FIG. 4A, and FIG. Sectional drawing of the joint part which shows a coupling | bonding state, the same figure (b) is the D section enlarged view of (a).

  The hydraulic pipe 1 is configured by combining a steel pipe, that is, a flare pipe 2 and a flexible hose 5 made of rubber or the like used for a portion having relative displacement, and a joint portion between the flare pipe 2 and the hose 5 A flare fitting 30 is used.

  The flare pipe joint 30 includes a collet 31 to which the hose 5 is connected and a flare nut 21 to which the flare pipe 2 is connected. The flare nut 21 and the flare pipe 2 are the same as those in the first embodiment, and detailed description thereof is omitted.

  The collet 31 is formed of a machined metal material such as iron, stainless steel, aluminum, brass or copper, and has a female screw hole 12 and a truncated cone portion 13 on one side and a hose on the other side as shown in FIG. 5 and the hose receiving port 16 are integrally formed, and an outward flange portion 17 is formed to protrude from the outer periphery.

  The female screw hole 12 includes a screw hole portion 12a on the opening side and an inner hole portion 12b on the bottom side, and the outer peripheral surface is gradually reduced in diameter toward the bottom portion 12c of the female screw hole 12 from the bottom portion 12c side to the opening side. A frustoconical portion 13 is formed so as to protrude, and a conical taper-like sealing surface 14 is formed on the outer peripheral surface of the frustoconical portion 13 so as to gradually decrease in diameter as it moves from the bottom 12c side to the opening side.

  The circular trapezoidal portion 13 is formed on the coaxial core with the communication hole 18 communicating the female screw hole 12 and the hose insertion tube 15 as the center, and the sealing surface 14 is the flare portion 3 formed at the tip of the flare tube 2. The shape is similar to the shape of the inner peripheral surface 3 a, and the communication hole 18 opens at the top end portion 13 a of the frustoconical portion 13. The tip 6 of the hose 5 is fitted into the hose insertion tube 15 and is crimped from the outside by a hose receiving port 16.

  Further, the seal surface 14 has a semicircular cross section and protrudes in an annular shape along the circumferential direction surrounding the through hole 18 and the top end portion 13 a of the frustoconical portion 13, and makes line contact with the inner peripheral surface 3 a of the flare portion 3 of the flare tube 2. An annular protrusion 32 that can be pressed in a state is formed. The annular protrusion 32 is in a range where it contacts the inner peripheral surface 3a of the flare portion 3 of the flare tube 2 in the coupled state, more specifically, the male screw portion 23 of the flare nut 21 is screwed into the screw hole portion 12a of the collet 31. When an axial pressing force is applied to the flare portion 3 of the flare pipe 2 by the pressure contact portion 24 of the flare nut 21 by tightening, the inner peripheral surface of the flare portion 3 at an initial stage prior to the seal surface 14 of the collet 31 It is formed in a range that abuts on 3a.

  In the flare pipe joint 30 configured as described above, the male screw portion 23 of the flare nut 21 is screwed into the screw hole portion 12a of the collet 31 in a state where the flare tube 2 is fitted into the through hole 22 of the flare nut 21. As a result, the flared portion 24 is formed on the top end of the annular protrusion 32 formed on the seal surface 14 of the collet 31 by applying an axial pressing force to the flared portion 3 of the flared tube 2 by the pressure contact portion 24 of the flared nut 21. 3 is brought into contact with the inner peripheral surface 3a in an annular manner in a line contact state.

  Further, when the flare nut 21 is tightened to apply an axial pressing force to the flare portion 3, an axial pressing force that presses against the top end of the annular protrusion 32 is applied by the inner peripheral surface 3 a of the flare portion 3, and the collet 31. The annular projection 32 formed on the seal surface 4 is pressed against the top end of the annular projection 32, and the annular projection 32 is plastically deformed according to the strength of the pressure contact force caused by the dimensional error of the partial thickness t of the flare portion 3. As shown in FIGS. 4A and 4B, the annular protrusion 32 formed on the seal surface 14 and the inner peripheral surface 3a of the flare portion 3 are in fluid-tight pressure contact with a uniform pressure contact force over the entire circumference. .

  Therefore, according to the joint portion structure configured as described above, the male threaded portion 23 of the flare nut 21 is screwed into the screw hole portion 12a of the collet 31 and tightened, and the flare tube 2 is connected via the pressure contact portion 24 of the flare nut 21. When an axial pressing force is applied to the flare portion 3, the inner peripheral surface 3 a of the flare portion 3 is formed on the seal surface 14, and press-contacts the annular protrusion 32 in an annular line contact state to impart plastic deformation to the annular protrusion 32. However, since the pressure contact is brought into a liquid-tight seal, the annular protrusion 32 is provided even when there is a dimensional error in the flare portion 3 such that the thickness t of the flare portion 3 of the flare tube 2 is partially uneven. Thus, a sealed state with a uniform pressure contact force is obtained, and liquid-tightness is not impaired, and a good sealed state is obtained.

  Further, since the annular protrusion 32 formed on the seal surface 14 is plastically deformed and the inner peripheral surface 3a of the flare portion 3 is pressed and sealed in a line contact state, the seal surface 14 of the collet 31 of the flare portion 3 is sealed. Accordingly, the tightening torque of the flare nut 21 can be reduced, the work efficiency is improved, and the work load on the worker is greatly reduced. Furthermore, the dimensional requirement accuracy of the flare part 3 of the frame tube 2 is relaxed, and reduction of productivity and manufacturing cost can be expected.

(Third embodiment)
A third embodiment will be described with reference to FIGS. 5 and FIG. 6, parts corresponding to those in FIG. 1 and FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 5A is a sectional view showing an exploded state of a joint portion of a hydraulic pipe 1 such as a brake pipe of a vehicle, for example. FIG. 5B is an enlarged view of a portion E of FIG. Sectional drawing of the joint part which shows a coupling | bonding state, the same figure (b) is the F section enlarged view of (a).

  The hydraulic pipe 1 is configured by combining a steel pipe, that is, a flare pipe 42 and a flexible hose 5 made of rubber or the like used for a portion having relative displacement, and a joint portion between the flare pipe 42 and the hose 5 is provided. A flare fitting 40 is used.

  The flare pipe joint 40 includes a collet 41 to which the hose 5 is connected and a flare nut 21 to which the flare pipe 42 is connected. The flare nut 21 is the same as in the first embodiment, and a detailed description thereof is omitted.

  The collet 41 is formed of a machined metal material such as iron, stainless steel, aluminum, brass or copper, and has a female screw hole 12 and a truncated cone portion 13 on one side and a hose on the other side as shown in FIG. 5 and the hose receiving port 16 are integrally formed, and an outward flange portion 17 is formed to protrude from the outer periphery.

  The female screw hole 12 includes a screw hole portion 12a on the opening side and an inner hole portion 12b on the bottom side, and the outer peripheral surface is gradually reduced in diameter toward the bottom portion 12c of the female screw hole 12 from the bottom portion 12c side to the opening side. A frustoconical portion 13 is formed so as to protrude, and a conical taper-like sealing surface 14 is formed on the outer peripheral surface of the frustoconical portion 13 so as to gradually decrease in diameter as it moves from the bottom 12c side to the opening side.

  The circular trapezoidal portion 13 is formed on the coaxial core with the communication hole 18 communicating the female screw hole 12 and the hose insertion tube 15 as the center, and the seal surface 14 is the flare portion 3 formed at the tip of the flare tube 42. The shape is similar to the shape of the inner peripheral surface 3 a, and the communication hole 18 opens at the top end portion 13 a of the frustoconical portion 13. The tip 6 of the hose 5 is fitted into the hose insertion tube 15 and is crimped from the outside by a hose receiving port 16.

  The flare tube 42 is formed of a metal material such as iron, stainless steel, aluminum, brass, or copper, and has an outer diameter that fits into the through hole 22 of the flare nut 21 as shown in FIG. A conical taper-shaped flare portion 3 that is gradually expanded in diameter as it moves to the tip end side is formed, and an inner peripheral surface 3 a of the flare portion 3 is formed in a shape similar to the shape of the seal surface 14 of the collet 41.

  Further, an annular protrusion 43 is formed on the inner peripheral surface 3a of the flare portion 3 and has a semicircular cross section in the circumferential direction, and protrudes in an annular shape surrounding the through hole 18 on the opposing seal surface 14 so as to be press-contactable in a line contact state. ing. The annular protrusion 43 is in a range where the annular protrusion 43 is annularly abutted with the seal surface 14 in a coupled state, more specifically, the male thread portion 23 of the flare nut 21 is screwed into the screw hole portion 12a of the collet 11 and tightened. When a pressing force in the axial direction is applied to the flare portion 3 of the flare tube 42 by the pressure contact portion 24, the pressure contact portion 24 is formed in a range that comes into contact with the seal surface 14 at an initial stage prior to the inner peripheral surface 3 a of the flare portion 3.

  In the flare pipe joint 40 thus configured, the male thread portion 23 of the flare nut 21 is connected to the screw hole portion 12a of the collet 31 in a state where the flare tube 42 is rotatably fitted in the through hole 22 of the flare nut 21. Of the annular protrusion 43 formed on the inner peripheral surface 3a of the flare portion 3 by applying an axial pressing force to the flare portion 3 of the flare tube 42 by the pressure contact portion 24 of the flare nut 21. The top end is brought into contact with the seal surface 14 in a line contact state.

  Further, when the flare nut 21 is tightened and an axial pressing force is applied to the flare portion 3, an axial pressing force that presses the annular protrusion 43 against the seal surface 14 is applied by the flare portion 3 to form the flare portion 3. The annular projection 43 is pressed against the seal surface 4 of the collet 41, and the annular projection 43 is plastically deformed according to the strength of the pressure contact force generated due to the dimensional error of the partial thickness t of the flare portion 3. 6 (a) and 6 (b), the annular protrusion 43 formed on the inner peripheral surface 3a of the flare portion 3 and the seal portion 14 are in pressure contact with the entire periphery of the annular protrusion 43 with a uniform pressure contact force. .

  Therefore, according to the joint structure configured in this way, the flare tube 42 is connected via the pressure contact portion 24 of the flare nut 21 by screwing the male screw portion 23 of the flare nut 21 into the screw hole portion 12a of the collet 41 and tightening. When an axial pressing force is applied to the flare portion 3, the annular protrusion 43 formed on the inner peripheral surface 3 a of the flare portion 3 is pressed against the seal surface 14 in a line contact state to impart plastic deformation to the annular protrusion 43. Even if there is a dimensional error in the flare portion 3 such that the thickness t of the flare portion 3 is partially formed unevenly because it is pressed and liquid-tightly sealed, the annular protrusion formed on the flare portion 3 43 is brought into contact with the sealing surface 14 with a uniform pressure contact force and liquid tightness is not impaired, and a good sealing state is obtained.

  Further, since the annular protrusion 43 formed on the flare portion 3 is pressed against the seal portion 14 with plastic deformation and sealed, the pressure contact force of the flare portion 3 against the seal surface 14 of the collet 41 can be reduced. In addition, the tightening torque of the flare nut 21 can be reduced, so that the work efficiency is improved and the work load on the worker is greatly reduced.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention. For example, in the first embodiment, the annular groove 19 formed in the through hole 18 is not limited to a semicircular cross section, and may be an annular groove having another cross sectional shape such as a triangular cross section. Also good. In addition, the annular protrusion 32 formed on the seal surface 14 in the second embodiment is not limited to a semicircular cross section, and may be an annular groove having another cross sectional shape such as a triangular cross section. Also good. Similarly, in the third embodiment, the annular projection 43 formed on the inner peripheral surface 3a of the flare portion 3 is not limited to a semicircular arc shape in cross section, and may be an annular groove having another cross sectional shape such as a triangular cross section. A groove may be formed.

It is a figure which shows sectional drawing of the joint part which shows the decomposition | disassembly state which concerns on 1st Embodiment of this invention, (a) shows a decomposition | disassembly state, (b) is the A section enlarged view of (a). (A) is sectional drawing which shows the combined state of a joint part, (b) is the B section enlarged view of (a). It is a figure which shows sectional drawing of the joint part which shows the decomposition | disassembly state which concerns on 2nd Embodiment of this invention, (a) shows a decomposition | disassembly state, (b) is the C section enlarged view of (a). (A) is sectional drawing which shows the joint state of a joint part, (b) is the D section enlarged view of (a). It is a figure which shows sectional drawing of the joint part which shows the decomposition | disassembly state which concerns on 3rd Embodiment of this invention, (a) shows a decomposition | disassembly state, (b) is the E section enlarged view of (a). (A) is sectional drawing which shows the joint state of a joint part, (b) is the F section enlarged view of (a). It is a figure which shows sectional drawing of the conventional joint part, (a) is sectional drawing which shows a decomposition | disassembly state, (b) is sectional drawing which shows a coupling | bonding state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydraulic piping 2 Flare pipe 3 Flare part 3a Inner peripheral surface 5 Hose 10 Flare fitting 11 Collet 12 Female screw hole 12c Bottom part 13 Frustum trapezoidal part 13a Top end part 14 Sealing surface 18 Communication hole 18a Inner peripheral surface 19 Annular groove 21 Flare nut 23 male threaded portion 24 pressure contact portion 30 flare fitting 31 collet 32 annular projection 40 flare fitting 41 collet 42 flare tube 43 annular projection

Claims (6)

A conical trapezoidal portion whose one end is projected and formed at the bottom of the female screw hole and moves toward the opening side, so that the outer peripheral surface is gradually reduced in diameter, and a communication hole opened at the top end of the frustoconical portion is formed, and A collet having a conical taper-shaped sealing surface formed on the outer peripheral surface of the frustoconical portion, and a pressure contact portion that is rotatably fitted to a flare tube having a flare portion at the tip and abuts against the flare at the tip The flare nut is provided with a male threaded portion that is screwed into the female screw hole. In the joint structure of the hydraulic piping that connects the flare pipe and the collet by pressing the circumferential surface to the sealing surface,
A joint for hydraulic piping, characterized in that a circumferentially continuous annular groove is formed on the inner peripheral surface of the communication hole in the corresponding axial range between the bottom of the female screw hole and the top end of the frustoconical portion. Part structure.   2. The joint structure for a hydraulic pipe according to claim 1, wherein the annular groove is formed within a plastic deformation range of the frustoconical portion formed by the flare portion being pressed against a seal surface. A conical trapezoidal portion whose one end is projected and formed at the bottom of the female screw hole and moves toward the opening side, so that the outer peripheral surface is gradually reduced in diameter, and a communication hole opened at the top end of the frustoconical portion is formed, and A collet having a conical taper-shaped sealing surface formed on the outer peripheral surface of the frustoconical portion, and a pressure contact portion that is rotatably fitted to a flare tube having a flare portion at the tip portion and abuts on the flare portion at the tip portion. The flare nut is provided with a male threaded portion that is screwed into the female screw hole. The male threaded portion of the flare nut is screwed into the female screw hole of the collet and tightened so that the inner portion of the flare portion is In the joint structure of the hydraulic piping that connects the flare pipe and the collet by pressing the circumferential surface to the sealing surface,
A joint structure for a hydraulic pipe, wherein an annular protrusion extending in the circumferential direction and in line contact with the inner peripheral surface of the flare portion is formed on the seal surface. The annular protrusion is
The press contact portion of the flare nut is formed in a range in which the flare portion of the flare tube is in contact with the inner peripheral surface of the flare portion at an initial stage when an axial pressing force is applied to the flare portion of the flare tube. Hydraulic piping joint structure. A conical trapezoidal portion whose one end is projected and formed at the bottom of the female screw hole and moves toward the opening side, so that the outer peripheral surface is gradually reduced in diameter, and a communication hole opened at the top end of the frustoconical portion is formed, and A collet having a conical taper-shaped sealing surface formed on the outer peripheral surface of the frustoconical portion, and a pressure contact portion that is rotatably fitted to a flare tube having a flare portion at the tip portion and abuts on the flare portion at the tip portion. The flare nut is provided with a male threaded portion that is screwed into the female screw hole. The male threaded portion of the flare nut is screwed into the female screw hole of the collet and tightened so that the inner portion of the flare portion is In the joint structure of the hydraulic piping that connects the flare pipe and the collet by pressing the circumferential surface to the sealing surface,
A joint structure for a hydraulic pipe, wherein an annular protrusion extending in the circumferential direction and in line contact with the seal surface of the collet is formed on the inner peripheral surface of the flare portion. The annular protrusion is
6. The hydraulic pipe according to claim 5, wherein the hydraulic pipe is formed in a range where it comes into contact with the seal surface of the collet at an initial stage when an axial pressing force is applied to the flare portion of the flare pipe by the pressure contact portion of the flare nut. Joint part structure.

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