JP2017032099A - Pipe joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bite-type pipe joint capable of securing sufficient deformation of a pipe, and reducing fastening torque.SOLUTION: A pipe joint (1) is a bite-type joint (1) for connecting a pipe (2) having an outer diameter of 19.05 mm or more and 38.10 mm or less. The pipe joint (1) includes a joint body (10) to which the pipe (2) is inserted, and a front ferrule (21) having an annular shape surrounding the circumference of the pipe (2) and having a tip portion (21A). In the pipe joint (1), a pipe clearance ratio as a ratio of a clearance (D1) between the joint body (10) and the pipe (2) in the radial direction, to a thickness (T1) in a radial direction of the tip portion (21A) is 0.3 or more and 0.8 or less.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pipe joint.

  Conventionally, it is a pipe joint used for a piping system of an air conditioner refrigerator, and is disposed between a joint body into which piping is inserted, a nut fastened to the joint body, and the joint body and the nut. There is known a pipe joint including a front ferrule and a back ferrule. This pipe joint is a bite type pipe joint that secures airtightness and pipe holding force by restraining the outer periphery of the pipe by the front ferrule and the back ferrule and deforming the pipe. Patent Document 1 below describes an example of such a double ferrule-type bite type joint.

JP 11-325342 A

  In the conventional bite type joint, it is necessary to obtain a desired amount of deformation of the pipe in order to ensure a constant pipe holding force, which causes a problem that the tightening torque increases.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a bite type pipe joint capable of sufficiently securing the deformation amount of the pipe and reducing the tightening torque. is there.

  A pipe joint (1) according to one aspect of the present invention is a bite-type pipe joint (1) for connecting pipes (2) having an outer diameter of 19.05 mm or more and 38.10 mm or less. The pipe joint (1) has a joint body (10) into which the pipe (2) is inserted, a ring shape surrounding the pipe (2), and a first tip (21A). 1 ferrule (21). In the pipe joint (1), the radial direction between the joint body (10) and the pipe (2) with respect to the thickness (T1) in the ring-shaped radial direction of the first tip portion (21A). The pipe gap ratio, which is the ratio of the gap (D1), is 0.3 or more and 0.8 or less.

  In the bite type pipe joint that connects pipes having an outer diameter of 19.05 mm or more and 38.10 mm or less, the present inventors have provided a measure for sufficiently securing the deformation amount of the pipe and reducing the tightening torque. We conducted an intensive study. As a result, the present inventors define the ratio of the pipe gap (gap between the joint body and the pipe) to the thickness of the ferrule tip (pipe gap ratio: pipe gap / ferrule tip thickness) within a predetermined range. As a result, the inventors have found that the above-mentioned problems can be solved and have arrived at the present invention.

  In a bite type pipe joint, the tightening torque increases as the ferrule deformation amount increases, and the pipe holding force increases as the pipe deformation amount increases. When the pipe gap ratio exceeds 0.8, the pipe gap is large and the thickness of the ferrule tip is small. When the pipe gap increases, the ratio of the ferrule change amount corresponding to the pipe gap in the total ferrule deformation amount increases, but this change amount does not contribute to the pipe deformation. Further, when the thickness of the ferrule tip is reduced, the strength is lowered, so that the tip portion warps when pressed against the pipe surface. The deformation amount of the ferrule due to this warping does not contribute to the deformation of the pipe. Therefore, when the pipe gap ratio exceeds 0.8, the ratio of the deformation amount that does not contribute to pipe deformation (the deformation amount corresponding to the pipe gap and the deformation amount due to warping of the tip) out of the total ferrule deformation amount increases. . Therefore, it is necessary to increase the deformation amount of the ferrule necessary for obtaining a desired piping deformation amount, and as a result, the tightening torque is greatly increased.

  On the other hand, when the pipe gap ratio is less than 0.3, the thickness of the ferrule tip is large and the pipe gap is small. When the thickness of the ferrule tip increases, the torque necessary for the deformation increases, and as a result, the tightening torque necessary for obtaining a desired amount of pipe deformation increases.

  On the other hand, in the said pipe joint (1), with respect to thickness (T1) in the radial direction of the 1st front-end | tip part (21A) of a 1st ferrule (21), a coupling main body (10), piping (2), The ratio of the gap (D1) in the radial direction (pipe gap ratio) is defined in the range of 0.3 to 0.8. Therefore, according to the pipe joint (1), it is possible to further reduce the tightening torque necessary for obtaining a desired pipe deformation amount. Therefore, according to the said pipe joint (1), the pipe joint excellent in workability | operativity can be provided by ensuring the deformation amount of piping (2) fully, and reducing fastening torque.

  In the pipe joint (1), the thickness (T1) in the radial direction of the first tip portion (21A) may be not less than 0.15 mm and not more than 0.60 mm.

  When the thickness (T1) exceeds 0.60 mm, the strength at the first tip (21A) increases, so that the torque required for deformation increases. On the other hand, when the thickness (T1) is less than 0.15 mm, the strength of the first tip portion (21A) decreases, so that warping tends to occur, and the tightening torque necessary to obtain the desired amount of pipe deformation. Rises. Therefore, the thickness (T1) is preferably in the range of 0.15 mm or more and 0.60 mm or less from the viewpoint of securing a desired pipe deformation amount and reducing the tightening torque.

  In the pipe joint (1), the ratio of the radial thickness (T0) of the pipe (2) to the outer diameter of the pipe (2) may be 0.03 or more and 0.13 or less.

  When the ratio of the wall thickness to the outer diameter of the pipe (2) exceeds 0.13, the wall thickness is excessive with respect to the outer diameter of the pipe (2), and the amount of fluid flowing in the pipe (2) is small. Become. On the other hand, when it is less than 0.03, the wall thickness becomes excessively small with respect to the outer diameter of the pipe (2), and the strength of the pipe (2) is lowered. Therefore, it is preferable that the ratio of the wall thickness to the outer diameter of the pipe (2) is 0.03 or more and 0.13 or less.

  The pipe joint (1) has an annular shape surrounding the circumference of the pipe (2), and is deformed radially inward of the annular shape by contacting the first ferrule (21). You may further provide the 2nd ferrule (22) which deform | transforms 2).

  According to the above configuration, the holding force of the pipe (2) is improved by deforming the second ferrule (22) and causing it to bite into the pipe (2), compared to the case where only the first ferrule (21) is provided. Can be made.

  In the pipe joint (1), the joint body (10) is a main body inclined surface (inner peripheral surface inclined at a first inclination angle (θ1) with respect to the axial direction (P) of the pipe (2) ( 11) may be included. The first ferrule (21) may be arranged such that the first tip (21A) is in contact with the inclined body (11). The first ferrule (21) faces the main body inclined surface (11) and has a second inclination angle (θ2) smaller than the first inclination angle (θ1) and the axial direction (P). It may have a ferrule inclined surface (23) inclined with respect to.

  According to the said structure, a 1st ferrule (21) can be smoothly moved in an axial direction (P) so that a 1st front-end | tip part (21A) may follow a main body inclined surface (11).

  In the pipe joint (1), the joint body (10) may be made of brass. The pipe (2) may be made of copper.

  According to the said structure, a 1st ferrule (21) can be made to bite into the surface of the said piping (2) easily by selecting comparatively soft copper as a material of piping (2). Moreover, the deformation | transformation when a 1st ferrule (21) contacts a joint main body (10) can be prevented by selecting a brass as a material of a joint main body (10).

  ADVANTAGE OF THE INVENTION According to this invention, the amount of deformation | transformation of piping can be ensured enough and the bite type pipe joint which can reduce a fastening torque can be provided.

It is the schematic which shows partially the cross-section of the pipe joint which concerns on one Embodiment of this invention. It is an enlarged view in the area | region II in FIG. It is the schematic which shows a mode that a ferrule tip deform | transforms at the time of nut fastening. It is the schematic which shows a mode that piping deform | transforms at the time of nut fastening. It is the schematic which shows a mode that the front-end | tip of a ferrule warps at the time of nut fastening. It is a graph which shows the relationship between a nut rotation angle and ferrule deformation amount, and the relationship between a nut rotation angle and fastening torque. It is a graph which shows the relationship between the pipe outer diameter and the ratio of the pipe gap to the pipe outer diameter. It is an enlarged view of the ferrule tip part concerning modification 1 of the above-mentioned embodiment. It is an enlarged view of the ferrule tip part concerning modification 2 of the above-mentioned embodiment. It is a graph which shows the relationship between piping clearance ratio and a deformation torque number.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Structure of pipe fitting>
First, the structure of the pipe joint 1 which concerns on one Embodiment of this invention is demonstrated with reference to FIG.1 and FIG.2. FIG. 1 partially shows a cross-sectional structure of the pipe joint 1 in a state before the nut 30 is fastened. FIG. 2 is an enlarged view of the pipe joint 1 in the region II shown in FIG.

  The pipe joint 1 is for connecting the pipes 2 in a refrigerator of an air conditioner, for example. In FIG. 1, only the right side of the connection portion between the pipes 2 of the pipe joint 1 is shown, but the left side also has the same cross-sectional structure, and the pipes 2 are connected via the pipe joint 1.

  The pipe joint 1 mainly includes a joint body 10, a front ferrule 21 (first ferrule), a back ferrule 22 (second ferrule), and a nut 30. As shown in FIG. 1, the pipe joint 1 includes a pipe 2 inserted into a joint body 10, a nut 30 is fastened to the joint body 10, and a front ferrule 21 interposed between the joint body 10 and the nut 30 and The outer periphery of the pipe 2 is restrained by the tip of the back ferrule 22. And the holding force and airtightness of the piping 2 are ensured by tightening the nut 30 to bite the tip and deforming the piping 2 radially inward.

  The pipe 2 has a cylindrical shape in which a hollow portion through which a fluid such as a refrigerant passes is formed. The pipe 2 is, for example, a copper pipe. The pipe 2 has an outer diameter of 19.05 mm or more and 38.10 mm or less. In the pipe 2, the ratio of the radial thickness T0 to the outer diameter (pipe thickness / pipe outer diameter) is in the range of 0.03 to 0.13. The pipe 2 is preferably made of copper that is easily deformed as in the present embodiment, but is not limited thereto, and may be made of aluminum or steel, for example. Further, the pipe 2 is not limited to the one for flowing the refrigerant, but may be one through which other fluid such as water or hot water flows.

  The joint body 10 is a brass member having a substantially cylindrical shape with a hollow portion formed therein. In the joint body 10, the inner diameter is larger than the outer diameter of the pipe 2, and an insertion hole into which the pipe 2 is inserted is formed on the inner peripheral surface side. The joint main body 10 is connected to the main body surface 12 which is an inner peripheral surface substantially parallel to the axial direction P of the pipe 2 and the main body surface 12 and is inclined with respect to the axial direction P at a first inclination angle θ1. A main body inclined surface 11 which is an inner peripheral surface. The main body inclined surface 11 is inclined radially outward so that the inner diameter is enlarged toward both end portions of the joint main body 10.

  A main body surface 12 of the joint main body 10 is formed with a contact portion 13 that protrudes inward in the radial direction and contacts one end of the pipe 2. The contact portion 13 is formed in an annular shape along the body surface 12 of the joint body 10. On the outer peripheral surface of the joint body 10, there is provided a grip portion 14 that is gripped by a general-purpose tool such as a spanner or a wrench when the nut 30 is fastened. The gripping portion 14 has a hexagonal outer shape when viewed from the axial direction P. On the outer peripheral surfaces at both ends of the joint body 10, body thread portions 15 that are fitted to the nut 30 when the nut 30 is fastened are formed.

  The nut 30 is a brass member having a ring shape, and is fitted on the joint body 10. The nut 30 includes a nut surface 31 that is an inner peripheral surface substantially parallel to the axial direction P of the pipe 2, a nut inclined surface 32 that is connected to the nut surface 31 and is inclined radially inward, and the nut inclination And a nut circumferential surface 34 that is connected to the surface 32 and defines an insertion hole into which the pipe 2 is inserted. A nut screw portion 33 is formed at the end of the nut surface 31 to be fitted to the main body screw portion 15 when the joint body 10 is fastened. Since the nut 30 is gripped and rotated by a tool such as a spanner or a wrench when fastened to the joint body 10, the outer shape when viewed from the axial direction P is a hexagonal shape.

  The front ferrule 21 is a brass member having an annular shape surrounding the periphery of the pipe 2, and the pipe 2 is inserted into a region on the inner peripheral surface side. The front ferrule 21 is disposed between the joint body 10 and the nut 30. The front ferrule 21 has a front end portion 21A (first front end portion) and a rear end portion 21B, and is configured such that the outer diameter gradually decreases from the rear end portion 21B toward the front end portion 21A. The front ferrule 21 has a distal end surface 25 that is an end surface of the distal end portion 21A, and the distal end surface 25 extends in a direction (radial direction) perpendicular to the axial direction P.

  The outer diameter of the front end surface 25 is larger than the outer diameter of the main body surface 12, and the inner diameter of the front end surface 25 is substantially the same as the inner diameter of the main body surface 12. Therefore, the front ferrule 21 is disposed so that the outer peripheral edge portion of the tip end portion 21 </ b> A contacts the main body inclined surface 11 in a state before the nut 30 is fastened (FIG. 1).

  The rear end portion 21B of the front ferrule 21 is provided with a rear end surface 21D substantially perpendicular to the axial direction P (substantially parallel to the radial direction) and a rear end inclined surface 21C connected to the inner end of the rear end surface 21D. ing. The rear end inclined surface 21C is inclined at a predetermined angle with respect to the radial direction so that the axial length of the front ferrule 21 decreases toward the inner side in the radial direction. In a state before the nut 30 is fastened (FIG. 1), a front end portion 22A of a back ferrule 22 described later contacts the rear end inclined surface 21C.

  The outer peripheral surface of the front ferrule 21 is configured as a ferrule inclined surface 23 that faces the main body inclined surface 11 in the radial direction. The ferrule inclined surface 23 is inclined with respect to the axial direction P at a second inclination angle θ2 smaller than the first inclination angle θ1 of the main body inclined surface 11. The difference (θ1−θ2) between the first inclination angle θ1 and the second inclination angle θ2 is not particularly limited, but is preferably in the range of 3 ° to 10 °.

  Similar to the front ferrule 21, the back ferrule 22 is a brass member having an annular shape surrounding the periphery of the pipe 2, and the pipe 2 is inserted into a region on the inner peripheral surface side. As shown in FIG. 1, the back ferrule 22 has substantially the same outer diameter and inner diameter as the front ferrule 21, and the axial length is smaller than that of the front ferrule 21. The back ferrule 22 is disposed between the joint body 10 and the nut 30 and is adjacent to the front ferrule 21 in the axial direction P.

  The back ferrule 22 has a front end 22A and a rear end 22B, and is configured such that the outer diameter gradually decreases from the rear end 22B toward the front end 22A. The back ferrule 22 is disposed so that the front end portion 22 </ b> A contacts the rear end inclined surface 21 </ b> C of the front ferrule 21 and the rear end portion 22 </ b> B contacts the nut inclined surface 32 before the nut 30 is fastened.

<Pipe clearance ratio of pipe joint>
Next, the tip thickness of the front ferrule 21 in the pipe joint 1, the gap between the joint body 10 and the pipe 2, and the relationship between them will be described with reference to FIG.

  The thickness T1 in the radial direction of the front end portion 21A of the front ferrule 21 is set to 0.15 mm or more and 0.60 mm or less, and more specifically 0.2 mm or more and 0.5 mm or less. The thickness T1 is the width in the radial direction of the distal end surface 25 that connects the inner peripheral surface 24 and the outer peripheral surface 23 (ferrule inclined surface) of the front ferrule 21 in the cross-sectional view of FIG.

  A pipe gap D <b> 1, which is a radial gap between the main body surface 12 of the joint body 10 and the outer peripheral surface of the pipe 2, is provided so as to be substantially constant in the axial direction P. The pipe gap D1 is (D2-D3) / 2, where D2 is the inner diameter of the joint body 10 including the main body surface 12, and D3 is the outer diameter of the pipe 2. In the pipe joint 1, a pipe gap ratio (pipe gap D1 (mm) / thickness T1 (mm)), which is a ratio of the pipe gap D1 to the thickness T1, is set to 0.3 or more and 0.8 or less, more specifically. Is set to 0.3 or more and 0.5 or less.

<Deformation process of ferrule and piping during nut fastening>
Next, the deformation process of the ferrules 21 and 22 and the pipe 2 when the nut 30 of the pipe joint 1 is fastened will be described with reference to FIGS. FIG. 1 shows a state before the nut 30 is tightened. FIG. 3 shows a state in which the front end 21 </ b> A of the front ferrule 21 is deformed during the tightening of the nut 30. FIG. 4 shows a state after the tightening of the nut 30 is completed.

  First, the pipe 2 is inserted into the joint body 10 as shown in FIG. Next, the front ferrule 21 and the back ferrule 22 are fitted into the pipe 2 in order, and then the nut 30 is fitted onto the joint body 10. Then, when the nut 30 is rotated and moved toward the joint body 10 in the axial direction P, tightening of the nut 30 is started. At this time, the back ferrule 22 is moved in the axial direction P by the rear end portion 22B being pushed by the nut inclined surface 32, and the front ferrule 21 is pushed in the axial direction P by the rear end portion 21B being pushed by the front end portion 22A of the back ferrule 22. Move to.

  The front end 21A of the front ferrule 21 starts to be deformed radially inward by being pressed against the main body inclined surface 11 as shown in FIG. Then, when the distal end portion 21A is deformed by the piping gap D1, it contacts the surface of the piping 2. As a result, the outer periphery of the pipe 2 is constrained by the tip portion 21 </ b> A of the front ferrule 21.

  Thereafter, the tightening of the nut 30 further proceeds, so that the surface of the pipe 2 is pressed by the front end portion 21 </ b> A of the front ferrule 21. Thereby, as shown in FIG. 4, the front end portion 21A of the front ferrule 21 bites into the surface of the pipe 2, and the pipe 2 is deformed radially inward.

  On the other hand, the front end portion 22A of the back ferrule 22 is deformed radially inward by being pressed against the rear end inclined surface 21C of the front ferrule 21. Thereby, the back ferrule 22 restrains the outer periphery of the pipe 2 by the tip portion 22 </ b> A, similarly to the front ferrule 21. As shown in FIG. 4, the pipe 2 can be deformed radially inward in the same manner as the front ferrule 21 by causing the tip 22 </ b> A to bite into the surface of the pipe 2. In this way, the piping 2 is deformed, and when the deformation amount reaches a predetermined amount, the tightening of the nut 30 is completed.

<Effect>
Next, the effect by the said pipe joint 1 is demonstrated.

  The pipe joint 1 is a bite-type pipe joint for connecting pipes 2 having an outer diameter of 19.05 mm or more and 38.10 mm or less, and includes a joint body 10 and a front ferrule 21. In the pipe joint 1, a pipe gap ratio (D1 / D1), which is a ratio of a gap (pipe gap) D1 in the radial direction between the joint body 10 and the pipe 2 to a thickness T1 in the radial direction of the distal end portion 21A of the front ferrule 21. T1) is 0.3 or more and 0.8 or less.

  The deformation amount of the front ferrule 21 when the nut of the pipe joint 1 is fastened includes a deformation amount corresponding to the pipe gap D1 and a deformation amount corresponding to the deformation of the pipe 2. When the pipe gap ratio (D1 / T1) exceeds 0.8, the pipe gap D1 is large and the thickness T1 of the ferrule tip is small. When the pipe gap D1 increases, the ratio of the amount of change that does not contribute to the deformation of the pipe 2 in the total deformation amount of the front ferrule 21 increases.

  Further, when the thickness T1 of the front end portion 21A of the front ferrule 21 is reduced, the strength is reduced. Therefore, when the surface of the pipe 2 is pressed by the tip 21A, the tip 21A warps as shown in FIG. The deformation amount of the front ferrule 21 due to the warping does not contribute to the deformation of the pipe 2. Thus, the phenomenon in which the tip portion 21A is warped remarkably appears when the pipe gap D1 is large. This is because the tip portion 21A after being warped easily enters the piping gap D1 as shown in FIG.

  Therefore, when the pipe gap ratio exceeds 0.8, the deformation amount that does not contribute to the deformation of the pipe 2 out of the total deformation amount of the front ferrule 21 (the deformation amount corresponding to the pipe gap D1, the warping of the tip portion 21A of the front ferrule 21) (Deformation amount due to) increases. Therefore, it is necessary to increase the amount of deformation of the front ferrule 21 necessary for obtaining a desired amount of deformation of the pipe 2, and as a result, the tightening torque is greatly increased.

  On the other hand, when the pipe gap ratio is less than 0.3, the thickness T1 of the front end portion 21A of the front ferrule 21 is large and the pipe gap D1 is small. As the thickness T1 of the distal end portion 21A increases, the torque required for the deformation increases. As a result, the tightening torque required to obtain the desired amount of deformation of the pipe 2 increases. Since the outer diameter of the pipe 2 is 19.05 mm or more and 38.10 mm or less, an increase in the tightening torque deteriorates workability.

  Here, changes in tightening torque due to the thickness of the ferrule tip as described above will be described with reference to the graph of FIG. The graph in FIG. 6A shows the relationship between the nut rotation angle and the ferrule deformation amount. In the graph of FIG. 6A, the horizontal axis indicates the nut rotation angle, and the vertical axis indicates the ferrule deformation amount. The graph in FIG. 6B shows the relationship between the nut rotation angle and the tightening torque. In the graph of FIG. 6B, the horizontal axis represents the nut rotation angle, and the vertical axis represents the tightening torque. The nut rotation angle on the horizontal axis corresponds to the amount of nut movement in the axial direction.

  6A and 6B, (1) is when the ferrule tip thickness is large, (2) is when the ferrule tip thickness is smaller than (1), and (3) is when the ferrule tip thickness is from (2). Each shows a small case where the tip is warped.

  In any of the cases (1) to (3), the ferrule deformation amount increases as the nut rotation angle increases (FIG. 6A), and the tightening torque also increases (FIG. 6B). Then, the deformation of the pipe starts from the time (the pipe deformation amount zero point) that is deformed by the pipe gap from the ferrule deformation amount zero point. Then, when the desired amount of pipe deformation is reached (tightening completion point), tightening of the nut is completed.

  First, comparing the cases of (1) and (2) with the same pipe deformation at the tightening completion point, the thickness of the ferrule tip is smaller (2) than in the case of (1). As a result, the tightening torque becomes small (t2 <t1).

  Next, comparing the cases of (2) and (3) at the same nut rotation angle, the amount of pipe deformation is smaller in the case of (3) in which the ferrule tip is warped than in the case of (2). . Therefore, in the case of (3), the nut rotation angle necessary for obtaining the same pipe deformation amount as in the case of (2) is increased, and as a result, the tightening torque is also increased (t2 <t3).

  In the pipe joint 1, the thickness T1 and the pipe gap D1 of the front end portion 21A of the front ferrule 21 are set so that the pipe gap ratio (D1 / T1) is in the range of 0.3 to 0.8. Yes. Therefore, according to the said pipe joint 1, the fastening torque required in order to obtain the desired amount of pipe deformation can be reduced, and the workability of pipe connection can be further improved.

  In the pipe joint 1, the thickness T1 of the front end portion 21A of the front ferrule 21 is not less than 0.15 mm and not more than 0.60 mm. When the thickness T1 exceeds 0.60 mm, the strength at the distal end portion 21A increases, so that the torque required for deformation increases. On the other hand, when the thickness T1 is less than 0.15 mm, the strength of the distal end portion 21A decreases, so that warping tends to occur, and the tightening torque necessary to obtain a desired amount of pipe deformation increases. Therefore, the thickness T1 is set in the range of 0.15 mm or more and 0.60 mm or less from the viewpoint of securing a desired amount of pipe deformation and reducing the tightening torque.

  In the pipe joint 1, the ratio of the radial thickness T0 of the pipe 2 to the outer diameter of the pipe 2 is 0.03 or more and 0.13 or less. When the ratio of the wall thickness to the outer diameter of the pipe 2 exceeds 0.13, the wall thickness becomes excessive with respect to the outer diameter of the pipe 2, and the amount of fluid flowing in the pipe 2 decreases. On the other hand, when it is less than 0.03, the wall thickness becomes excessively small with respect to the outer diameter of the pipe 2, and the strength of the pipe 2 is lowered. Therefore, the ratio of the wall thickness to the outer diameter of the pipe 2 is set to 0.03 or more and 0.13 or less.

  The pipe joint 1 includes a back ferrule 22 that deforms radially inward by abutting the front ferrule 21 to deform the pipe 2. Thereby, the holding power and airtightness of the pipe 2 can be improved as compared with a single ferrule-type pipe joint. The back ferrule 22 is not an essential configuration and may be omitted.

  In the pipe joint 1, the joint main body 10 has a main body inclined surface 11 that is inclined with respect to the axial direction P at a first inclination angle θ 1. The front ferrule 21 is disposed so that the tip 21A comes into contact with the main body inclined surface 11 before the nut is fastened (FIG. 1). The front ferrule 21 has a ferrule inclined surface 23 that is inclined with respect to the axial direction P at a second inclination angle θ2 that is smaller than the first inclination angle θ1. Thereby, the front ferrule 21 can be smoothly moved in the axial direction P so that the tip 21 </ b> A follows the inclined body 11 when the nut is fastened.

<Pipe outer diameter design>
The reason why the outer diameter of the pipe 2 is set in the range of 19.05 mm or more and 38.10 mm or less will be described with reference to FIG. FIG. 7 is a graph showing the relationship between the pipe outer diameter (horizontal axis) and the ratio of the pipe gap to the pipe outer diameter (vertical axis).

  In a bite type pipe joint, basically, as the pipe outer diameter increases, the pipe gap and the ferrule tip thickness increase. The pipe gap is set to facilitate the insertion of the pipe at the time of construction, but the pipe tolerance (including roundness) changes around the outer diameter of 19.05 mm. There is an inflection point in relation to the outer diameter. That is, the inclination is different between the pipe outer diameter of less than 19.05 mm (especially 15.88 mm or less) and 19.05 mm or more, and when it is less than 19.05 mm, the pipe gap is the original value. Is set larger than. Therefore, in this embodiment, the lower limit value of the outer diameter of the pipe 2 is set to 19.05 mm in order to clearly define the relationship (pipe gap ratio) between the pipe gap and the ferrule tip thickness.

  When the outer diameter of the pipe 2 exceeds 38.10 mm, the pipe gap and the ferrule tip are excessively thick, and the tightening torque is greatly increased. Therefore, in this embodiment, the upper limit value of the outer diameter of the pipe 2 is set to 38.10 mm.

<Modification 1>
Next, the shape of the front ferrule 41 which concerns on the modification 1 of the said embodiment is demonstrated with reference to FIG. FIG. 8 is an enlarged view of the front ferrule 41 according to the first modification in the vicinity of the first tip portion 41A.

  The front end surface 45 of the front ferrule 41 includes a flat surface portion 48 located on the inner diameter side, and a first curved surface portion 46 connected to the flat surface portion 48 and located on the outer diameter side. That is, the front ferrule 41 is modified so as to exclude the corner portion on the outer diameter side (shaded portion in FIG. 8) in the shape exemplified in the above embodiment. The thickness T2 in the radial direction of the first tip portion 41A includes a connection point P1 between the tip surface 45 and the inner peripheral surface 44, an extension line of the tip surface 45 (broken line in the figure), and an extension line of the ferrule inclined surface 43 (see FIG. It is defined by the length between the intersection point P2 and the middle broken line).

<Modification 2>
Next, the shape of the front ferrule 51 which concerns on the modification 2 of the said embodiment is demonstrated with reference to FIG. FIG. 9 is an enlarged view of the front ferrule 51 according to the second modification in the vicinity of the first tip portion 51A.

  The front end surface 55 of the front ferrule 51 includes a second curved surface portion 58 located on the inner diameter side and a third curved surface portion 56 located on the outer diameter side. That is, the front ferrule 51 is modified so as to exclude the corner portions (shaded portions in FIG. 9) on the inner diameter side and the outer diameter side in the shape exemplified in the above embodiment. A straight line L1 connecting the extension line of the inner peripheral surface 54 and the extension line of the ferrule inclined surface 53 is in contact with the tip surface 55 at the contact point P1. The thickness T3 in the radial direction of the first tip 51A is defined by the length of the straight line L1.

<Experimental example>
The effect of the ratio of the pipe gap to the thickness of the front ferrule tip (pipe gap ratio: pipe gap / front ferrule tip thickness) on the tightening torque was investigated. Specifically, pipe joints designed for various pipe clearance ratios were prepared, and the tightening torque when the pipe deformation amount was made constant was measured. Then, the relationship between the piping gap ratio and the tightening torque was investigated.

  FIG. 10 is a graph showing the survey results. In the graph of FIG. 10, the horizontal axis indicates the pipe gap ratio, and the vertical axis indicates the number of deformation torques. Here, the number of deformation torques is defined to exclude the influence of the pipe outer diameter from the measured tightening torque data, and the measured value of the tightening torque is divided by the square value of the pipe outer diameter. Can be obtained.

  As is clear from FIG. 10, the deformation torque is greater when the pipe gap ratio is in the range of 0.3 to 0.8 than when the pipe gap ratio is greater than 0.8 and less than 0.3. The number has become smaller. In particular, there was a minimum value of the number of deformation torques within the piping gap ratio range of 0.3 to 0.5. From this result, the tightening torque required to obtain a predetermined amount of pipe deformation is reduced by setting the pipe gap ratio to 0.3 to 0.8 (preferably 0.3 to 0.5). I found it possible.

  It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Pipe joint, 2 piping, 10 joint main body, 11 main body inclined surface, 21 front ferrule (1st ferrule), 21A front-end | tip part (1st front-end | tip part), 22 back ferrule (2nd ferrule), 23 ferrule inclination Surface, T0, T1 thickness, D1 piping gap (gap), P-axis direction, θ1 first inclination angle, θ2 second inclination angle

Claims (6)

A bite type pipe joint (1) for connecting pipes (2) having an outer diameter of 19.05 mm or more and 38.10 mm or less,
A joint body (10) into which the pipe (2) is inserted;
A first ferrule (21) having a ring shape surrounding the pipe (2) and having a first tip (21A);
The ratio of the gap (D1) in the radial direction between the joint body (10) and the pipe (2) to the ring-shaped radial thickness (T1) of the first tip (21A). A pipe joint (1) having a pipe gap ratio of 0.3 to 0.8.   The pipe joint (1) according to claim 1, wherein the thickness (T1) in the radial direction of the first tip portion (21A) is not less than 0.15 mm and not more than 0.60 mm.   The pipe joint (1) according to claim 1 or 2, wherein a ratio of a radial thickness (T0) of the pipe (2) to an outer diameter of the pipe (2) is 0.03 or more and 0.13 or less.   A second ring having a ring shape surrounding the circumference of the pipe (2) and deforming the pipe (2) by deforming radially inward of the ring shape by contacting the first ferrule (21). The pipe joint (1) according to any one of claims 1 to 3, further comprising a ferrule (22). The joint main body (10) has a main body inclined surface (11) which is an inner peripheral surface inclined at a first inclination angle (θ1) with respect to the axial direction (P) of the pipe (2).
The first ferrule (21) is:
The first tip (21A) is disposed so as to contact the main body inclined surface (11),
A ferrule inclined surface (23) facing the main body inclined surface (11) and inclined with respect to the axial direction (P) at a second inclination angle (θ2) smaller than the first inclination angle (θ1). The pipe joint (1) according to any one of claims 1 to 4, comprising: The joint body (10) is made of brass,
The pipe joint (1) according to any one of claims 1 to 5, wherein the pipe (2) is made of copper.

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