JP5953410B1 - Pipe joint structure - Google Patents

Abstract

There is provided a pipe joint structure that can be connected by tightening with a small force without requiring a large force, and that can be securely and firmly connected without a risk of coming out even when a strong pulling force is applied to the pipe. In a pipe joint structure having a cap nut 3 screwed to a male thread portion 2 of a joint body 1 and connecting a thin metal tube 4, the cap nut 3 is a taper that is reduced in diameter toward the tip opening side. Provided with a retaining ring 5 having a tapered inner peripheral surface 6, a tapered surface 7 on the outer periphery, and a locking projection 8 formed on the inner peripheral surface, and a predetermined length from the tip edge 4 a of the thin metal tube 4. A plastically processed groove 9 is formed at the position, and the cap nut 3 is screwed onto the male screw portion 2, and the tapered inner peripheral surface 6 presses the tapered surface 7 to reduce the diameter of the retaining ring 5, and is inserted. The engaging projection 8 is configured to be engaged with the recessed groove 9 of the thin metal tube 4. [Selection] Figure 1

Description

  The present invention relates to a pipe joint structure.

  Conventionally, as a pipe joint, by screwing the male thread portion of the retainer into the tapered female thread portion of the joint body, the outer top portions of a plurality of small disks protruding from the inner peripheral surface of the retainer bite into the outer peripheral surface of the pipe. A pipe that is configured not to be pulled out in the axial direction is known (see Patent Document 1).

Japanese Patent No. 312385

  However, since the pipe joint described in Patent Document 1 causes the small disk to spiral into the pipe body gradually and deeply around the outer peripheral surface of the pipe, a very large tightening force is required to screw the retainer into the joint body. The work efficiency is poor. In particular, connection work at a high place was difficult. In addition, since it is structured to prevent pulling out by several small discs that bite into the outer peripheral surface of the pipe, if a strong pulling force is applied to the pipe after connection is completed, it may come off leaving a longitudinal scratch on the outer peripheral surface of the pipe. Or, there is a possibility that the small disk is broken and the pipe comes off.

  Therefore, the present invention can be connected by tightening with a small force without requiring a large force, it is easy to connect at a high place, and there is no possibility of coming out even if a strong pulling force is applied to the pipe, It aims at providing the pipe joint structure which can be connected reliably and firmly.

The pipe joint structure according to the present invention is a pipe joint structure including a cap nut screwed to the male thread portion of the joint main body, and connecting the thin metal pipe. The joint main body includes the inserted thin metal pipe. A circumferential abutting step portion with which the leading edge of the sleeve abuts is provided, and has a tip surface orthogonal to the axial center, and the cap nut has a tapered inner peripheral surface that is reduced in diameter toward the tip opening side. A C-shaped annular retaining ring having a tapered surface on the outer periphery and a locking projection formed on the inner peripheral surface, and a plastic working groove at a predetermined position from the tip edge of the thin metal tube is formed, by screwing completion status to the male screw portion of the cap nut, with the retainer ring is in contact with the front end surface of said joint body, the tapered inner circumferential surface of the cap nut is and pressing the tapered surface, as the retainer ring is reduced in diameter shape by pressing pressure, insert Above the groove of the thin metal tube that is intended the engaging convexed latch portion is in locked state.

Further, in a pipe joint structure that includes a cap nut screwed to the male thread portion of the joint main body and connects the thin metal pipe, the joint main body has a circumferential surface on which the tip edge of the inserted thin metal pipe abuts. A stepped portion is provided, and has a tip surface orthogonal to the axis, and the cap nut has a tapered inner peripheral surface that is reduced in diameter toward the tip opening side, and has a tapered surface on the outer periphery. And a C-shaped annular retaining ring in which a plurality of annular independent protrusions are formed on the inner peripheral surface, and a plurality of plastic working independent recessed grooves are formed at predetermined positions from the leading edge of the thin metal tube. provided, in screwing completion status to the male screw portion of the cap nut, with the retainer ring is in contact with the front-end surface of said joint body, the tapered inner circumferential surface of the cap nut is the The taper surface is pressed, and the retaining ring is reduced in diameter by the pressing, A plurality of said discrete concave peripheral groove of the thin metal tube that is input, but a plurality of said discrete protrusions is in the locked state.
The thin metal pipe is a stainless steel pipe defined in JIS G3448.

According to the pipe joint structure of the present invention, it is possible to connect a thin metal pipe by fitting a retaining ring into a recessed groove (concave groove) that has been plastically processed in advance, and to connect the thin metal pipe, and to rotate the cap nut (torque) Is very small. The cap nut can be screwed manually and smoothly, making the work easier and convenient for connecting pipes at various locations. In particular, even when the worker connects the pipe at a high place such as the back of the ceiling, it is not time-consuming, so the work can be performed quickly and smoothly. With a simple structure, it is possible to surely obtain a retaining state with an extremely large pull-out prevention force, and prevent the thin metal tube from being unexpectedly pulled out after construction. It can be manufactured at low cost and the construction cost can be reduced.

It is a section side view of the state before insertion which shows one embodiment of the present invention. It is a cross-sectional side view of the state which inserted the thin metal pipe. It is a cross-sectional side view which shows a retaining state. It is a principal part expanded sectional side view of FIG. It is a perspective view which shows a retaining ring. It is a perspective view which shows the retaining ring as a reference example . It is an explanatory perspective view which shows a mode that a thin metal tube is cut | disconnected. It is a cross-sectional side view which shows a mode that a ditch | groove is plastically processed to a thin metal pipe. It is a cross-sectional side view of the state before insertion which shows other embodiment of this invention. It is a cross-sectional side view of the state which inserted the thin metal pipe. It is a cross-sectional side view which shows a retaining state. It is sectional drawing which shows a retaining ring. It is a cross-sectional side view which shows a mode that an independent concave circumferential groove is plastically processed to a thin metal pipe. It is a section side view of the state before insertion which shows the 1st reference example . It is a cross-sectional side view which shows a retaining state. It is sectional drawing which shows a retaining ring. It is a cross-sectional side view which shows a mode that a convex part is plastically processed to a thin metal pipe. It is a section side view of the state before insertion which shows the 2nd reference example . It is a cross-sectional side view which shows a retaining state. It is sectional drawing which shows a retaining ring. It is a cross-sectional side view which shows a mode that an independent protrusion is plastically processed to a thin metal pipe.

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments.
As shown in FIG. 1, the pipe joint structure according to the present invention includes a joint body 1 with a male screw portion 2 into which a distal end portion of a thin metal pipe 4 is inserted, and a cap nut 3 screwed into the male screw portion 2. Is provided.
In the joint body 1, a holding groove portion 20 that holds a sealing material 10 such as an O-ring is formed on the inner peripheral surface. Moreover, the joint main body 1 is formed with a circumferential contact step portion 21 in contact with the distal end edge 4a of the inserted thin metal tube 4 at the back thereof.

The cap nut 3 has a tapered inner peripheral surface 6 that allows the thin metal tube 4 to be inserted and is reduced in diameter toward the tip opening side. Further, the cap nut 3 has a female screw portion 24 that is screwed onto the male screw portion 2 of the joint body 1.
On the inner side of the cap nut 3, a retaining ring 5 having a locking projection 8 on the inner peripheral surface is disposed. The retaining ring 5 has a tapered surface 7 on its outer periphery that can slide on the tapered inner peripheral surface 6.

As shown in FIG. 5, the retaining ring 5 is formed in a C-shaped annular shape having a cut 26 at one place. Although the locking projection 8 is formed as a trapezoidal low protrusion in the figure, it may be a low protrusion with an arc cross section (not shown). The retaining ring 5 is made of synthetic resin or stainless steel. In addition, you may use the metal which does not raise | generate an electric corrosion even if it contacts with the coupling main body 1, the cap nut 3, and the thin metal pipe 4. FIG. As a reference example, the retaining ring 5 shown in FIG. 6 has the cut 26 (shown in FIG. 5) omitted, and instead, a plurality of slits 27 are formed alternately in the axial direction. 27, the shape is provided with elasticity capable of reducing the diameter in the radial inward direction.

As shown in FIG. 1, the thin metal tube 4 has a concave groove 9 formed by plastic working at a predetermined position slightly away from the tip edge 4a.
As shown in FIG. 2, when the thin metal tube 4 is inserted until the leading edge 4 a comes into contact with the circumferential bump 21, the groove 9 is formed so as to correspond to the locking projection 8 of the retaining ring 5. Is formed over the entire circumference at a position separated from the tip edge 4a by a certain length dimension L.

The thin metal pipe 4 is a stainless steel pipe defined in JIS G3448, and is mainly used for piping such as water supply / hot water supply or drainage.
Table 1 shows the relationship between the outer diameter D of the thin metal pipe 4 and the wall thickness t. The thin metal tube 4 preferably has an outer diameter D set to 20 mm to 50 mm and a wall thickness t set to 1.0 mm to 1.2 mm.

  As shown in FIG. 7, the thin metal tube 4 is cut into a predetermined length by a rotary tube cutter 40 in advance before connection. The tube cutter 40 includes a frame 45 having a pair of rollers 46 and 46, and a slide bar 42 pivotally attached to a tip end portion thereof and slidably held on the frame 45, and the slide bar 42 rotates. A free feed adjustment knob 43 is provided. When cutting the thin metal tube 4, the slide bar 42 is retracted while pushing the latch 44 to sufficiently widen the distance between the cutter wheel 41 and the rollers 46, 46, and the thin metal tube 4 is placed on the rollers 46, 46. Place. The feed adjustment knob 43 is pressed to move the slide bar 42 forward, and the cutter wheel 41 is brought into contact with the thin metal tube 4. Next, the feed adjustment knob 43 is rotated (clockwise), and the thin metal tube 4 is firmly fixed by the cutter wheel 41 and the pair of rollers 46 and 46. The tube cutter 40 is revolved around the thin metal tube 4 and rolled while pressing the cutter wheel 41 against the outer peripheral surface of the thin metal tube 4. Rotate the feed adjustment knob 43 little by little (clockwise) every one or two turns until the cutter wheel 41 bites into the outer peripheral surface of the thin metal tube 4 until the thin metal tube 4 is completely cut. Repeat this operation. By cutting the thin metal tube 4 in this way, the tip edge 4a is formed perpendicular to the axis, and the tip edge 4a is formed on a beautiful end face with little unevenness. Since the thin metal tube 4 is cut while being pressed against the cutter wheel 41 from the radial outer direction, the tip edge 4a is generally plastic in an inwardly bent shape as shown in FIGS. It is deformed.

  After cutting the thin metal tube 4, the plastic working concave groove 9 is formed in the thin metal tube 4 by the grooving jig 30 as shown in FIG. 8. The grooving jig 30 has an insertion shaft portion 37 that can be inserted into the thin metal tube 4 at the distal end portion of the frame 35, and a recessed portion 36 a that receives the back side of the recessed groove 9 is formed at the distal end of the insertion shaft portion 37. The formed backing roller 36 is pivotally mounted rotatably. The frame 35 slidably holds the slider 32, and the slider 32 has a convex roller 31 rotatably at the tip, and a rotatable feed adjustment knob 33 is provided at the base end. Yes. When the plastic working concave groove 9 is formed in the thin metal tube 4, the slider 32 is retracted to sufficiently widen the gap between the convex roller 31 and the backing roller 36, and the insertion shaft portion 37 is inserted into the thin metal tube 4. At the same time, the leading edge 4 a of the thin metal tube 4 is brought into contact with the side end surface of the frame 35. The feed adjustment knob 33 is pressed to bring the convex roller 31 into contact with the outer peripheral surface of the thin metal tube 4, and then the feed adjustment knob 33 is rotated (clockwise) to bring the convex roller 31 into the thin metal tube 4. Press against the outer peripheral surface of At this time, the backing roller 36 presses the position corresponding to the convex roller 31 from the inner peripheral surface of the thin metal tube 4. The thin metal tube 4 is firmly fixed by pressing the outer peripheral surface against the convex roller 31 and the inner peripheral surface against the backing roller 36 at a predetermined position slightly away from the tip edge 4a. The grooving jig 30 is revolved around the thin metal tube 4, and the convex roller 31 is rolled on the outer peripheral surface of the thin metal tube 4. The feed adjustment knob 33 is rotated (clockwise) while the grooving jig 30 is revolved, and the outer peripheral surface of the thin metal tube 4 is gradually recessed by the convex roller 31 to form the plastically processed groove 9. . In this way, the concave groove 9 can be easily and stably formed with high accuracy at a position separated from the tip edge 4a by a certain length L.

  In the pipe joint structure of the present invention described above, the procedure for connecting the thin metal tube 4 will be described. As shown in FIG. 2, after inserting the thin metal tube 4 into the cap nut 3, the tip of the thin metal tube 4 is inserted. The part is inserted into the joint body 1. The thin metal tube 4 is pushed by pushing until the leading edge 4a of the thin metal tube 4 comes into contact with the circumferential abutting step portion 21, and the thin metal tube 4 is positioned, and the concave groove 9 formed at a predetermined position from the leading edge 4a is prevented It is disposed at a position corresponding to the locking projection 8 of the ring 5.

As shown in FIGS. 3 and 4, with the thin metal tube 4 inserted, the cap nut 3 is manually rotated to be screwed onto the male screw portion 2, and the tapered inner peripheral surface 6 is connected to the tapered surface 7. A radial inward pressing force F is applied while sliding, and the retaining ring 5 is reduced in diameter. The retaining ring 5 is compressed by being sandwiched between the joint main body 1 and the cap nut 3, and the retaining projection 8 is retained in the recessed groove 9 of the inserted thin metal pipe 4. The locking convex portion 8 is fitted in the recessed groove 9 in a press-contact state over almost the entire circumference (excluding the cut 26), and the thin metal tube 4 is connected in a strong retaining state. The screwing operation of the cap nut 3 can be performed manually with a sufficiently small force, and a tool such as a pipe wrench is not necessary, but may be performed using a tool. Further, swallow depth _{L 0} of the thin metal tube 4 is set to be 1.25 times to 1.8 times the outer diameter D. When swallowing depth L ₀ of the thin metal tube 4 is less than 1.25 times the outer diameter D, and when a strong force from the radial outside direction (folding direction of the force) is exerted on the thin-walled metal tube 4, metal There is a possibility that the tube 4 cannot be securely held and pulled out. Further, when the swallow depth L ₀ of the thin metal tube 4 is greater than 1.8 times the outer diameter D, and the joint body 1 is too large, undesirably. In this way, by satisfying 1.25D ≦ L ₀ ≦ 1.8D, the thin metal tube 4 is sufficiently durable without being pulled out even when a force (bending moment) in the folding direction is applied, and is a compact tube A joint is obtained.

Next, another embodiment of the pipe joint structure of the present invention will be described.
As shown in FIG. 9, a cap nut 3 is provided that is screwed onto the male thread portion 2 of the joint body 1.
In the pipe joint structure for connecting the thin metal pipe 4 (G3448), the cap nut 3 has a tapered inner peripheral surface 6 that is reduced in diameter toward the tip opening side, and an inner peripheral surface on the inner side of the cap nut 3 A retaining ring 15 having a plurality of annular independent ridges 16, 16, 16 is provided.
In the joint body 1, a holding groove 20 that holds a sealing material 10 such as an O-ring is formed on the inner peripheral surface, and the distal end edge 4 a of the inserted thin metal tube 4 is formed at the back of the joint body 1. A stepped portion 21 that is in contact with the circumferential contact is formed. The joint body 1 is formed such that the stepped portion 21 is slightly narrower than the inner diameter of the thin metal tube 4 so that the distal end edge 4a plastically deformed in an inwardly curved shape is surely hit.
The cap nut 3 has a female screw portion 24 that can be inserted into the thin metal tube 4 and is screwed to the male screw portion 2 of the joint body 1.

As shown in FIG. 12, the retaining ring 15 has a tapered surface 17 on the outer periphery, and two to four annular independent ridges 16, 16, 16 are formed on the inner peripheral surface.
The retaining ring 15 is made of synthetic resin or stainless steel, and is formed in a C-shaped annular shape having a cut 26 at one place. The retaining ring 15 may have a shape in which a plurality of slits are alternately formed in the axial direction (as shown in FIG. 6).

As shown in FIG. 9, the thin metal tube 4 is formed with a plurality of independent concave circumferential grooves 18, 18, 18 by plastic working at a predetermined position slightly away from the tip edge 4a.
As shown in FIG. 10, when the thin metal tube 4 is inserted until the tip edge 4 a comes into contact with the circumferential contact step portion 21, two to four wires correspond to the independent protrusions 16, 16, 16. In the illustrated example, three independent concave circumferential grooves 18, 18, 18 are formed over the entire circumference of the thin metal tube 4 in a belt-like region E that is separated from the tip edge 4 a by a certain length L.

After the thin metal tube 4 is cut to a predetermined length by the rotary tube cutter 40 shown in FIG. 7, a plurality of independent concave circumferential grooves 18, 18 are formed by plastic working with a grooving jig as shown in FIG. , 18 are formed.
The independent concave circumferential grooves 18, 18, 18 are formed by pressing a pressing roller 50 having a plurality of annular convex portions 50 a, 50 a, 50 a against the outer peripheral surface of the thin metal tube 4. At this time, it is desirable to apply a receiving roller 49 indicated by a two-dot chain line in the figure from the inner peripheral surface of the thin metal tube 4. The independent concave circumferential grooves 18, 18, 18 can be stably and highly accurately formed at a predetermined position slightly away from the distal end edge 4 a of the thin metal tube 4, are easy to plastically process, and are thin metal There is an advantage that the amount of decrease in the inner diameter of the tube 4 can be reduced. That is, in FIG. 9, a plurality of (three) concave circumferential grooves 18, 18, 18 are used in order to exert the same pulling resistance as compared with the single concave groove. Since the groove depths of the grooves 18, 18 and 18 may be shallow, the inner diameter dimension Di shown in FIG. 9 can be set larger than in the case of the above one (see FIG. 1). Therefore, the passage resistance of water or the like can be reduced. In particular, the cutting of the rotary tube cutter 40 illustrated in FIG. 7 inevitably causes the tip edge 4a to undergo a reduced diameter deformation as shown in FIGS. 1 and 9, and the reduced diameter inner diameter at that time is denoted by Dx. In this case, Di> Dx can be obtained, and there is an advantage that the fluid passage resistance accompanying the (necessary) tip diameter reduction deformation is hardly increased any more.

The use method (action) of the pipe joint structure of the present invention shown in FIGS. 9 to 11 will be described.
As shown in FIG. 10, after the thin metal tube 4 is inserted through the cap nut 3, the tip of the thin metal tube 4 is inserted into the joint body 1. The thin metal tube 4 is pushed by pushing until the leading edge 4a of the thin metal tube 4 comes into contact with the circumferential abutting step portion 21, so that the thin metal tube 4 is positioned and independent concave circumferential grooves 18, 18 formed at predetermined positions from the leading edge 4a. , 18 are arranged at positions corresponding to the independent protrusions 16, 16, 16 of the retaining ring 5.

As shown in FIG. 11, the cap nut 3 is manually rotated to be screwed onto the male screw portion 2, and a radial inward pressing force F is applied while the tapered inner peripheral surface 6 is brought into sliding contact with the tapered surface 17. Thus, the diameter of the retaining ring 15 is reduced. The retaining ring 15 is sandwiched and compressed between the joint body 1 and the cap nut 3 and is inserted into the plurality of independent concave circumferential grooves 18, 18, 18 of the thin metal pipe 4 inserted therein. 16 are locked. The independent protrusions 16, 16, 16 and the independent concave circumferential grooves 18, 18, 18 are press-contacted over almost the entire circumference (except for the cut), and the concave and convex portions are fitted to each other, so that the thin metal tube 4 is strong. It will be connected in a state that is not pulled out. The screwing operation of the cap nut 3 can be performed manually with a sufficiently small force, and a tool such as a pipe wrench is unnecessary. Further, swallow depth _{L 0} of the thin metal tube 4 is set to be 1.25 times to 1.8 times the outer diameter D. When swallowing depth L ₀ of the thin metal tube 4 is less than 1.25 times the outer diameter D, and when a strong force from the radial outside direction (folding direction of the force) is exerted on the thin-walled metal tube 4, metal There is a possibility that the tube 4 cannot be securely held and pulled out. Further, when the swallow depth L ₀ of the thin metal tube 4 is greater than 1.8 times the outer diameter D, and the joint body 1 is too large, undesirably.

Next, a first reference example related to the pipe joint structure of the present invention will be described.
As shown in FIG. 14, in a pipe joint structure that includes a cap nut 3 that is screwed onto the male thread portion 2 of the joint body 1 and connects the thin metal pipe 4 (according to JIS G3448), the thin metal pipe 4 A plastic working convex portion 14 is formed at a predetermined position from the tip edge 4a, and a retaining ring 12 having a locking groove 13 formed on the inner peripheral surface is provided. The retaining ring 12 is fitted to the thin metal tube 4 as a fitting shape.
In the joint body 1, a holding groove portion 20 that holds a sealing material 10 such as an O-ring is formed on the inner peripheral surface. Moreover, the joint main body 1 is formed with a circumferential contact step portion 21 in contact with the distal end edge 4a of the inserted thin metal tube 4 at the back thereof.
The cap nut 3 has a tapered inner peripheral surface 6 that is inserted through the thin metal tube 4 before the convex portion 14 is plastically processed and is reduced in diameter toward the distal end opening side. Further, the cap nut 3 has a female screw portion 24 that is screwed onto the male screw portion 2 of the joint body 1.

  As shown in FIG. 15, when the thin metal tube 4 is inserted until the tip edge 4 a comes into contact with the circumferential contact step portion 21, just before the retaining ring 12 hits the end surface of the joint body 1, or just contacts. It is arranged as follows. The convex portion 14 is formed over the entire circumference at a predetermined position slightly away from the tip edge 4a. In FIG. 14, the convex part 14 is arrange | positioned by the fixed length dimension L from the front-end edge 4a, and is formed in the cross-sectional trapezoid shape by plastic working. In addition, the convex part 14 may be formed in cross-sectional arc shape.

  As shown in FIG. 16, the retaining ring 12 has a tapered surface 11 on the outer periphery, and a locking groove 13 having a rectangular or trapezoidal cross section that can be fitted to the convex portion 14 is formed on the inner peripheral surface. Has been. The retaining ring 12 is made of synthetic resin or stainless steel, and is formed in a C-shaped annular shape having a cut 26 at one place.

After the thin metal tube 4 is cut into a predetermined length by the rotary tube cutter 40 shown in FIG. 7, the cap nut 3 is inserted into the thin metal tube 4, and as shown in FIG. The convex portion 14 is plastically processed in the thin metal tube 4.
The tool 55 has an insertion shaft portion 57 that can be inserted into the thin metal tube 4 at the distal end portion of the frame 54, and a convex roller 56 in which a small protrusion 56 a is formed at the distal end of the insertion shaft portion 57. It is pivotally attached so that it can rotate freely. Further, the frame 54 slidably holds the slider 52, and the slider 52 has a roller 51 with a concave groove at its distal end so as to be rotatable, and a rotatable feed adjustment knob 53 is provided at its proximal end. It has been. When the plastic working convex portion 14 is formed on the thin metal tube 4, the slider 52 is retracted to sufficiently widen the gap between the concave grooved roller 51 and the convex roller 56, so that the insertion shaft portion 57 is connected to the thin metal tube 4. And the front edge 4a of the thin metal tube 4 is brought into contact with the side end surface of the frame 54. The feed adjustment knob 53 is pressed to bring the concave grooved roller 51 into contact with the outer peripheral surface of the thin metal tube 4, and then the feed adjustment knob 33 is rotated (clockwise) to turn the concave groove grooved roller 51. Press against the outer peripheral surface of the thin metal tube 4. At this time, the convex roller 56 presses the position corresponding to the concave circumferential grooved roller 51 from the inner peripheral surface of the thin metal tube 4. The thin metal tube 4 is firmly fixed at a predetermined position slightly away from the tip edge 4a by pressing the outer peripheral surface against the concave grooved roller 51 and the inner peripheral surface against the convex roller 56. The feed adjustment knob 53 is rotated (clockwise) while the tool 55 revolves around the thin metal tube 4, and the outer peripheral surface of the thin metal tube 4 is plastically processed little by little by the grooved roller 51 and the convex roller 56. Thus, the convex portion 14 is formed. In this way, the convex portion 14 can be easily and stably formed with high accuracy at a position apart from the tip edge 4a by a certain length L, and plastic processing is easy, and There is an advantage that it is not necessary to reduce the inner diameter of the thin metal tube 4. That is, the passage resistance of water or the like in the thin metal tube 4 can be reduced as compared with the case where the concave groove 9 is formed in the thin metal tube 4 in FIG. The cutting of the rotary tube cutter 40 illustrated in FIG. 7 inevitably causes the tip edge 4a to undergo a diameter reduction deformation, and as shown in FIG. There is no need to increase it any more. Further, since the inner diameter dimension of the thin metal tube 4 does not decrease after the convex portion 14 is formed, there is an advantage that the insertion shaft portion 57 can be easily pulled out and work efficiency can be improved.

As shown in FIGS. 14 to 15, the procedure for connecting the thin metal tube 4 will be described. After the cap nut 3 is inserted into the thin metal tube 4, the retaining ring 12 is fitted to the convex portion 14. At this time, the retaining ring 12 is elastically deformed so as to have a diameter larger than the outer diameter D of the thin metal tube 4, and the retaining ring 12 is elastically arranged so that the convex portion 14 fits into the retaining groove 13. Restore and fit.
Next, the tip of the thin metal tube 4 is inserted into the joint body 1. The tip edge 4a of the thin metal tube 4 comes into contact with the stepped portion 21 in the circumferential contact, and the thin metal tube 4 is positioned. The retaining ring 12 fitted to the convex portion 14 is disposed at a position immediately before hitting the joint body 1.

As shown in FIG. 15, with the thin metal tube 4 inserted, the cap nut 3 is screwed onto the male thread portion 2, and the tapered inner peripheral surface 6 is slidably contacted with the tapered surface 11 to apply the pressing force F. By applying, the convex portion 14 of the inserted thin metal tube 4 is locked in the locking groove 13. The retaining ring 12 is sandwiched and compressed between the joint body 1 and the cap nut 3, and the convex portion 14 and the locking groove 13 are fitted in a pressure contact state, so that the thin metal tube 4 is connected in a strong retaining state. Is done. The screwing operation of the cap nut 3 can be performed manually with a sufficiently small force. Further, the swallowing depth L ₀ of the thin metal tube 4 is set to be 1.25 to 1.8 times the outer diameter D. When the depth L ₀ of the thin metal tube 4 is less than 1.25 times the outer diameter D, when a strong force (force in the folding direction) is applied to the thin metal tube 4 from the radial outer direction, the metal There is a possibility that the tube 4 cannot be securely held and pulled out. Further, when the swallow depth L ₀ of the thin metal tube 4 is greater than 1.8 times the outer diameter D, and the joint body 1 is too large, undesirably. In this way, by satisfying 1.25D ≦ L ₀ ≦ 1.8D, the thin metal tube 4 is sufficiently durable without being pulled out even if a force (bending moment) in the folding direction is applied, and is a compact tube A joint is obtained.

Next, a second reference example will be described.
As shown in FIG. 18, in a pipe joint structure that includes a cap nut 3 that is screwed onto the male thread portion 2 of the joint body 1 and connects the thin metal pipe 4 (according to JIS G3448), the thin metal pipe 4 A plurality of annular independent ridges 22, 22, 22 are formed by plastic working at a predetermined position from the tip edge 4a, and a plurality of independent concave circumferential grooves 23, 23, 23 are formed on the inner peripheral surface. A retaining ring 25 is provided, and the retaining ring 25 is fitted to the thin metal tube 4 with the plurality of independent concave circumferential grooves 23, 23, 23 being fitted on the independent protrusions 22, 22, 22.
In the joint body 1, a holding groove 20 that holds a sealing material 10 such as an O-ring is formed on the inner peripheral surface, and the distal end edge 4 a of the inserted thin metal tube 4 is formed at the back of the joint body 1. A stepped portion 21 that is in contact with the circumferential contact is formed. The joint body 1 is formed such that the stepped portion 21 is slightly narrower than the inner diameter of the thin metal tube 4 so that the distal end edge 4a plastically deformed in an inwardly curved shape is surely hit.
The cap nut 3 has a female screw portion 24 that can be inserted into the thin metal tube 4 and is screwed to the male screw portion 2 of the joint body 1.

As shown in FIG. 20, the retaining ring 15 has a tapered surface 28 on the outer periphery, and two to four independent concave circumferential grooves 23, 23, 23 are formed on the inner peripheral surface.
The retaining ring 15 is made of synthetic resin or stainless steel, and is formed in a C-shaped annular shape having a cut 26 at one place. The retaining ring 15 may have a shape in which a plurality of slits are alternately formed in the axial direction (as shown in FIG. 6).

  As shown in FIG. 19, when the thin metal tube 4 is inserted until the tip edge 4 a contacts the circumferential bump 21, just before the retaining ring 25 hits the end face of the joint body 1, or just It arrange | positions so that it may contact | connect. Two to four (three in the illustrated example) annular independent ridges 22, 22, 22 are formed over the entire circumference of the thin metal tube 4 in a belt-like region E separated from the tip edge 4 a by a certain length L. Has been.

After the thin metal tube 4 is cut into a predetermined length by the rotary tube cutter 40 shown in FIG. 7, the cap nut 3 is inserted into the thin metal tube 4, and the thin metal tube 4 is cut by a tool 60 as shown in FIG. 21. A plurality of annular independent ridges 22, 22, 22 are plastically processed.
The tool 60 applies a roller 66 having a plurality of annular protrusions to the inner peripheral surface of the thin metal tube 4 and presses a roller 61 having a plurality of concave grooves on the outer peripheral surface of the thin metal tube 4. The other configuration is the same as that of the tool 55 in FIG. According to the tool 60, a plurality of annular independent ridges 22, 22, 22 can be stably formed with high accuracy at a predetermined position slightly away from the tip edge 4 a of the thin metal tube 4, and plastic working There is an advantage that the inner diameter dimension of the thin metal tube 4 does not need to be reduced. Accordingly, it is possible to reduce the passage resistance of water or the like without increasing the fluid passage resistance accompanying the (necessary) tip diameter reduction deformation due to cutting. In addition, after forming the independent protrusions 22, 22, 22, there is an advantage that the tool 60 can be easily pulled out and work efficiency can be improved.

A usage method (action) of the second reference example shown in FIGS. 18 and 19 will be described.
As shown in FIG. 18, after the cap nut 3 is inserted through the thin metal tube 4, the retaining ring 25 is fitted to the independent protrusions 22, 22, 22. At this time, the retaining ring 25 is elastically deformed to be larger than the outer diameter D of the thin metal tube 4 so that the independent ridges 22, 22, 22 fit into the independent concave circumferential grooves 23, 23, 23. Next, the retaining ring 25 is elastically restored and fitted.
Next, the tip of the thin metal tube 4 is inserted into the joint body 1. The tip edge 4a of the thin metal tube 4 comes into contact with the stepped portion 21 in the circumferential contact, and the thin metal tube 4 is positioned. The retaining ring 25 fitted to the independent protrusions 22, 22, 22 is disposed at a position immediately before hitting the joint body 1.

As shown in FIG. 19, the cap nut 3 is manually rotated to be screwed onto the male screw portion 2, and a radial inward pressing force F is applied while the tapered inner peripheral surface 6 is brought into sliding contact with the tapered surface 28. As a result, the plurality of independent protrusions 22, 22, 22 of the inserted thin metal pipe 4 are engaged with the plurality of independent concave circumferential grooves 23, 23, 23. The retaining ring 25 is compressed by being sandwiched between the joint body 1 and the cap nut 3, and the plurality of independent protrusions 22, 22, 22 and the independent concave circumferential grooves 23, 23, 23 are fitted (engaged) with each other, The thin metal pipe 4 is connected in a strong retaining state. The screwing operation of the cap nut 3 can be performed manually with a sufficiently small force, and a tool such as a pipe wrench is unnecessary. Further, swallow depth _{L 0} of the thin metal tube 4 is set to be 1.25 times to 1.8 times the outer diameter D. When swallowing depth L ₀ of the thin metal tube 4 is less than 1.25 times the outer diameter D, and when a strong force from the radial outside direction (folding direction of the force) is exerted on the thin-walled metal tube 4, metal There is a possibility that the tube 4 cannot be securely held and pulled out. Further, when the swallow depth L ₀ of the thin metal tube 4 is greater than 1.8 times the outer diameter D, and the joint body 1 is too large, undesirably.

  The present invention is not limited to the above-described embodiment, and the design can be changed without changing the gist thereof. For example, the joint body 1 shows only a part (in a cross section). The entirety of 1 is of various types such as straight, elbow, cheese, socket, etc. Further, the same structure may be formed on the other end side outside the figure. The sealing material 10 fitted to the inner peripheral surface of the joint body 1 may be U packing or the like other than the O-ring.

As described above, the pipe joint structure according to the present invention includes a cap nut 3 screwed to the male screw portion 2 of the joint body 1, At a pipe joint structure for connecting the thin metal tube 4, the joint body 1 Is provided with a circumferential abutting step portion 21 with which the distal end edge 4a of the inserted thin metal tube 4 abuts, and has a distal end surface that is orthogonal to the axial center, and the cap nut 3 extends toward the distal end opening side. A C-shaped annular retaining ring 5 having a tapered inner peripheral surface 6 with a reduced diameter, a tapered surface 7 on the outer periphery and a locking projection 8 formed on the inner peripheral surface, and a thin metal A plastic working concave groove 9 is formed at a predetermined position from the distal end edge 4a of the tube 4, and the cap nut 3 is screwed onto the male threaded portion 2 to bring the retaining ring 5 into contact with the distal end surface of the joint body 1. , thin gold tapered inner peripheral surface 6 of the cap nut 3 is reduced in diameter the retaining ring 5 presses the tapered surface 7, it is inserted Since the locking convex portion 8 is configured to be locked in the concave groove 9 of the tube 4, when the cap nut 3 is screwed to the male screw portion 2 to reduce the diameter of the retaining ring 5, plastic working is performed in advance. The thin metal tube 4 can be connected by fitting the locking projection 8 into the recessed groove 9, and the rotational torque (tightening force) of the cap nut 3 can be very small. The cap nut 3 can be manually and smoothly screwed in. The work is easy and convenient for connecting various places and pipes. In particular, even when the worker connects the pipe at a high place such as the back of the ceiling, it is not time-consuming, so the work can be performed quickly and smoothly. With a simple structure, it is possible to reliably obtain a retaining state with a large pulling prevention force and prevent the thin metal tube 4 from being unexpectedly pulled out after construction. It can be manufactured at low cost and the construction cost can be reduced.

In addition, in the pipe joint structure that includes the cap nut 3 that is screwed onto the male thread portion 2 of the joint body 1 and that connects the thin metal pipe 4, the joint body 1 has the tip edge of the inserted thin metal pipe 4. 4a is provided with a circumferential contact stepped portion 21 that abuts and has a tip surface that is orthogonal to the axial center, and the cap nut 3 has a tapered inner peripheral surface 6 that is reduced in diameter toward the tip opening side. And a C-shaped annular retaining ring 15 having a tapered surface 17 on the outer periphery and a plurality of annular independent protrusions 16, 16, 16 formed on the inner peripheral surface, and the leading edge of the thin metal tube 4. A plurality of independent concave circumferential grooves 18, 18, 18 are formed by plastic working at a predetermined position from 4 a, the cap nut 3 is screwed onto the male screw portion 2, and the retaining ring 5 is connected to the distal end surface of the joint body 1. is brought into contact, the tapered inner peripheral surface 6 of the cap nut 3 is a retainer ring 15 presses the tapered surface 17 Since the plurality of independent protrusions 16, 16, 16 are configured to be engaged with the plurality of independent concave circumferential grooves 18, 18, 18 of the thin metal pipe 4 that is inserted into the diameter, the cap nut 3 is When the retaining ring 5 is reduced in diameter by being screwed onto the male thread portion 2, the annular independent protrusions 16, 16, 16 are fitted into the plurality of independent concave circumferential grooves 18, 18, 18 that have been plastically processed in advance. The thin metal pipe 4 can be connected, and the rotational torque (tightening force) of the cap nut 3 can be very small. The cap nut 3 can be manually and smoothly screwed in. The work is easy and convenient for connecting various places and pipes. In particular, even when the worker connects the pipe at a high place such as the back of the ceiling, it is not time-consuming, so the work can be performed quickly and smoothly. With a simple structure, it is possible to reliably obtain a strong retaining state with an extremely large pull-out preventing force, and to prevent the thin metal tube 4 from being unexpectedly pulled out after construction. It can be manufactured at low cost and the construction cost can be reduced. Easy plastic working of independent concave peripheral groove 18,18,18, and requires less amount of decrease in inner diameter of the thin metal tube 4, Ru can be reduced passage resistance of the fluid (pressure loss).

Also, thin-walled metal tube 4, since the stainless steel defined in JIS G3448, leading edge 4a when cleaved (by a tube cutter 40), but slightly shrink-deformed, vertical shape to axis In addition, the end edge 4a can be formed on a beautiful end face with few irregularities, and the groove 9 can be formed easily, stably and with high precision at a distance of a certain length L from the end edge 4a. can do. When for screwing the cap nut 3 to the male screw portion 2, a thin walled metal tube 4 is elastically deformed, irregularities obtained firm retaining state fitted without any clearance, securely connect the thin metal tube 4 it can.

1 joint body 2 male threaded portion 3 bags nut 4 thin metal tube 4a leading edge 5 retainer ring 6 tapered inner peripheral surface 7 tapered surface 8 locking projections 9 plastic working concave groove
1 5 retaining ring 16 annular independent ridge 17 taper surface 18 independent concave circumferential groove
21 Stepped part against circumferential bump

Claims (3)

In a pipe joint structure comprising a cap nut (3) screwed to the male thread part (2) of the joint body (1) and connecting a thin metal pipe (4),
The joint body (1) is provided with a circumferential contact step portion (21) with which the tip edge (4a) of the inserted thin metal pipe (4) abuts, and the tip surface of the axial orthogonal surface Have
The cap nut (3) has a tapered inner peripheral surface (6) that is reduced in diameter toward the tip opening side,
A C-shaped annular retaining ring (5) having a tapered surface (7) on the outer periphery and a locking projection (8) formed on the inner peripheral surface, and the tip of the thin metal tube (4) A plastic working groove (9) is formed at a predetermined position from the edge (4a),
The retaining ring (5) is in contact with the distal end surface of the joint body (1) when the cap nut (3) is screwed onto the male threaded portion (2). The tapered inner peripheral surface (6) of (3) presses the tapered surface (7), and the retaining ring (5) is reduced in diameter by the pressing so that the thin metal tube is inserted. The pipe joint structure according to (4), wherein the locking projection (8) is locked in the concave groove (9). In a pipe joint structure comprising a cap nut (3) screwed to the male thread part (2) of the joint body (1) and connecting a thin metal pipe (4),
The joint body (1) is provided with a circumferential contact step portion (21) with which the tip edge (4a) of the inserted thin metal pipe (4) abuts, and the tip surface of the axial orthogonal surface Have
The cap nut (3) has a tapered inner peripheral surface (6) that is reduced in diameter toward the tip opening side,
A C-shaped annular retaining ring (15) having a tapered surface (17) on the outer periphery and a plurality of annular independent protrusions (16) (16) (16) formed on the inner peripheral surface; and A plurality of plastic working independent concave circumferential grooves (18) (18) (18) are provided at predetermined positions from the tip edge (4a) of the thin metal pipe (4),
The retaining ring (5) is in contact with the distal end surface of the joint body (1) when the cap nut (3) is screwed onto the male threaded portion (2). The tapered inner peripheral surface (6) of (3) presses the tapered surface (17), and the retaining ring (15) is reduced in diameter by the pressing, and the thin metal tube is inserted. A pipe joint characterized in that the plurality of independent protrusions (16), (16) and (16) are in a locked state in the plurality of independent concave circumferential grooves (18), (18) and (18) of (4) Construction.   The pipe joint structure according to claim 1 or 2, wherein the thin metal pipe (4) is a stainless steel pipe defined in JIS G3448.

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