JP2007162730A - Hose coupling - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hose coupling which successfully metal seals a female pipe and a male pipe even when a lateral force in the direction perpendicular to the axis is applied owing to the hose bending, etc., and causes no risk of oil leakage, etc., even when impact is applied after the fastening work. <P>SOLUTION: The hose coupling 10 comprises a metal adapter 16 having a female taper surface 30, a nipple fitting 14 having a male taper surface 36, and a cap nut 18. The male taper surface 36 is brought into press contact with the female taper surface 30 by screwing the cap nut 18 into a male screw 32, and the nipple fitting 14 and the adapter 16 are fastened by metal sealing of metal-to-metal contact with each other, to connect the hose and opponent equipment side. The end of the male taper surface 36 has an arcuately curved surface having a radius of 0.5 to 2.0 mm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hose joint for connecting a hose and a counterpart device side, and more particularly to a hose joint for fastening a male pipe and a female pipe in a sealed state with a metal seal.

Conventionally, as a hose joint for connecting a hose and a counterpart device side, (a) a metal female tube having a female tapered surface on the inner peripheral side and a metal male tube having a male tapered surface on the outer peripheral side And a cap nut that fastens them in the axial direction.
Here, the cap nut is provided with an inward annular locking protrusion that is locked in an annular locking groove formed on one outer peripheral side of the male tube and the female tube at one end in the axial direction, and the other outer periphery. The other end in the axial direction is provided with a female threaded portion that is screwed into the male threaded portion formed on the surface, and the male tapered surface is pressed against the female tapered surface by screwing the cap nut into the male threaded portion, so that the metal The male pipe and the female pipe are fastened in a sealed state with a metal seal by contact, and the hose and the counterpart device side are connected via the hose joint.

For example, Patent Literature 1 and Patent Literature 2 below disclose this type of hose joint.
FIG. 7 shows an example of a conventional hose joint.
In the figure, reference numeral 200 denotes a hose joint, a nipple fitting (male pipe) 204 fixed to the hose 202, a metal adapter (female pipe) 206 attached and fixed to the counterpart device side, and screwing them in the axial direction. And a cap nut 208.

The nipple fitting 204 has an insertion portion 210. The insertion portion 210 is inserted into the hose 202, and in this state, is fixed to the hose 202 together with the socket fitting 211 that is caulked and fixed to the outer peripheral surface of the hose 202. It is like that.
The adapter 206 has a female fitting portion 212.
A female tapered surface 214 is formed on the inner peripheral side of the distal end portion of the female fitting portion 212, and a male screw portion 216 is formed on the outer peripheral surface.
On the other hand, the nipple fitting 204 has a male fitting portion 218, and a male tapered surface 220 is formed on the outer peripheral side of the tip portion.

Here, the female taper surface 214 and the male taper surface 220 basically have the same taper angle (angle formed with the axial direction), but strictly speaking, as shown in the partially enlarged view of FIG. The taper angle of the male tapered surface 220 with respect to the surface 214 is a small angle by a minute angle.
For example, when the taper angle of the female taper surface 214 is an angle within the range of 0 to +30 ′ (min) with respect to 30 °, the taper angle of the male taper surface 220 is 0 to −30 ′ (min) with respect to 30 °. The angle is within the range.

An annular locking groove 222 is formed on the outer peripheral surface of the male fitting portion 218 of the nipple fitting 204.
On the other hand, the cap nut 208 is provided with an inward annular locking projection 224 at one end in the axial direction and a female screw portion 226 at the other end in the axial direction.

In the hose coupling 200, the female threaded portion 226 of the cap nut 208 is screwed into the male threaded portion 216 of the adapter 206 with the annular locking projection 224 of the cap nut 208 locked in the annular locking groove 222 of the nipple fitting 204. The nipple fitting 204 and the adapter 206 are fastened in the axial direction.
At this time, the male tapered surface 220 of the nipple fitting 204 and the female tapered surface 214 of the adapter 206 are pressed in the axial direction based on the screw fastening force by the cap nut 208, and the nipple fitting 204 and the adapter 206 are brought into contact with each other by metal contact. Metal seal.

The male taper surface 220 and the female taper surface 214 are not in full contact with each other on their mating surfaces, and as shown in the partial enlarged view of FIG. The taper surface 220A and the female taper surface 214 are in linear contact with the female taper surface 214 and are in contact with each other. Sealing with the surface 214 is performed (because the taper angle of the male taper surface 220 is slightly smaller than the taper angle of the female taper surface 214).
And based on the screw fastening by the cap nut 208 of this nipple metal fitting 204 and the adapter 206, the hose 202 and the other apparatus side are connected in the sealing state.

In the case of the hose joint 200, the male tapered surface 220 is aligned with the female tapered surface 214 and the cap nut 208 is screwed in a state where the hose 202 is oriented in the insertion direction of the nipple fitting 204 as shown in FIG. , The nipple fitting 204 and the adapter 206 can be fastened with a good seal.
Specifically, the nipple fitting 204 and the adapter 206 can be fastened in a state where the tip corner portion 220A of the male taper surface 220 is bitten into the female taper surface 214 over the entire circumference.

However, when a force (lateral force) perpendicular to the axis is applied to the nipple fitting 204, for example, when the hose 202 is forcibly bent largely as shown in FIG. It has been found that the target seal state may not be obtained when the fastening operation is performed.
And when this inventor performed various tests in order to clarify the reason, it turned out that this sealing defect arises by the following phenomena.

FIG. 9 schematically shows the cause of such a seal failure.
As shown in FIG. 8, when the screw fastening with the cap nut 208 is performed in a state where the hose 202 is greatly bent, that is, in a state where a lateral force in the direction perpendicular to the axis is applied to the nipple fitting 204, the male tapered surface 220 is used. state but inclined not enter the straight in the axial direction with respect to the female tapered surface 214, i.e. the male tapered surface 220 in a state in which the axis P ₂ is inclined nipple fitting 204 with respect to the axis P ₁ of the adapter 206 is a female taper 9A. In the state of entering the surface 214, only the lower part (the lower end and the vicinity thereof) in FIG. 9I of the tip corner portion 220A of the male tapered surface 220 partially abuts and bites into the female tapered surface 214. In other words, the same portion is caught on the female tapered surface 214.

In such a state, even if the cap nut 208 is tightened with a specified tightening torque (standard tightening torque), the male tapered surface 220 does not sufficiently enter the female tapered surface 214, and finally the male tapered surface. The surface 220 is in a single-contact state with respect to the female tapered surface 214 and is not press-contacted over the entire circumference, so that the metal seal is not uniformly performed over the entire circumference.
If any impact is applied thereafter in such an unstable state, the nipple fitting 204 is in the stable state shown in FIG. 9 (II), that is, the direction in which the axis P ₂ coincides with the axis P ₁ of the adapter 206. The angle of the tip 220A of the male taper surface 220 with respect to the female taper surface 214 is removed, the fastening of the nipple fitting 204 and the adapter 206 is loosened, and the pressure contact between the male taper surface 220 and the female taper surface 214 is reduced. The force decreases and this causes oil leakage (when the transport fluid is oil).

  Although it may be possible to increase the tightening torque of the cap nut 208, there is no guarantee that a good metal seal between the male tapered surface 220 and the female tapered surface 214 will be obtained. It becomes easy to raise | generate a metal fitting crack, and the intensity | strength improvement of a metal fitting is needed, and it brings about a cost increase.

JP 2002-340248 A JP 2003-148661 A

  The present invention is based on the above circumstances, and even when a female pipe and a male pipe are screw-fastened with a cap nut in a state where a lateral force in a direction perpendicular to the axis is applied by bending a hose or the like, these female pipes In addition, the present invention has been made for the purpose of providing a hose joint that can satisfactorily metal seal a male pipe and that does not cause oil leakage even when an impact is applied after the fastening operation.

  Thus, according to the first aspect, (a) a metal female pipe having a female tapered surface on the inner peripheral side, and (b) a male tapered surface having a taper angle smaller than the female tapered surface on the outer peripheral side. A metal male pipe and (c) an inward annular locking projection that is locked in an annular locking groove formed on the outer peripheral side of one of the male pipe and the female pipe. A cap nut having a female screw portion screwed into a male screw portion formed on the other outer peripheral surface at the other end portion in the axial direction, and screwing the cap nut into the male screw portion. In the hose joint for connecting the hose and the counterpart device side, the male taper surface is pressed against the female taper surface and the male tube and the female tube are fastened in a sealed state with a metal seal by contact between metals. The cross-sectional shape of the tip of the male tapered surface is an arc-shaped curved surface with a radius of 0.5 to 2.0 mm over the entire circumference. It is characterized in.

  According to a second aspect of the present invention, in the first aspect, the curved surface shape is an arc shape having a radius of 0.7 to 1.3 mm.

Effects and effects of the invention

As described above, in the present invention, the shape (cross-sectional shape) of the tip of the male tapered surface is an arcuate curved surface shape (R shape) having a radius of 0.5 to 2.0 mm over the entire circumference.
In this case, when the male tube and the female tube are fastened with the cap nut, the male taper surface enters obliquely with respect to the female taper surface, and the tip of the male taper surface temporarily becomes the female taper surface. Even if a state where the single taper hits one another occurs, it is possible to prevent the tip of the male tapered surface from excessively biting into the female tapered surface.
Further, as the cap nut is further tightened, the direction of the male taper surface with respect to the female taper surface can be automatically corrected by the R-shaped guide action at the tip of the male taper surface so that their axes coincide with each other. The tip of the taper surface can be uniformly pressed against the female taper surface over the entire circumference, and a stable and good sealing state can be realized.

By the way, when the present inventor made a test by making the tip of the male tapered surface into an arcuate curved surface shape (R shape) and gradually increasing the curvature radius thereof, the curvature radius becomes larger than a certain value. On the other hand, it has been found that there is a problem that leads to a decrease in sealing performance.
This is because, when the tip of the male taper surface has such an R shape, the contact surface of the tip of the male taper surface with respect to the female taper surface becomes wide under the fastening state of the female tube and the male tube, and the male taper surface As a result, the contact pressure at the tip of the male taper surface with respect to the female taper surface decreases under the same tightening torque, and this reduces the sealing performance. It is thought to invite.

Thus, as a result of the study by the present inventors, it has been found that the curvature radius of the curved surface at the tip of the male tapered surface is preferably in the range of 0.5 to 2.0 mm.
The range of 0.7 to 1.6 mm is more desirable, and the range of 0.7 to 1.3 mm is particularly desirable (Claim 2).

  According to the present invention as described above, when a male pipe and a female pipe of a hose joint are fastened with a cap nut in a state in which a lateral force in a direction perpendicular to the axis is applied, a bag is simply used even if not a skilled worker. By simply tightening the nut, the male tube and the female tube can be fastened stably under a good sealing condition, and the female tube and the male tube are fastened in an unstable state. It is possible to satisfactorily solve problems that later cause oil leakage and the like.

Next, an embodiment in the case where the present invention is applied to a hose joint for connecting a hydraulic oil for hydraulic oil and a counterpart equipment (hydraulic equipment) will be described in detail with reference to the drawings.
In FIG. 1, reference numeral 10 denotes a hose joint, which is a nipple fitting (male pipe) 14 fixed to a hose 12 that transports hydraulic oil, a metal adapter (female pipe) 16 that is attached and fixed to the counterpart device side, and And a cap nut 18 that is screwed in the axial direction.

The nipple fitting 14 has an insertion portion 20, and the insertion portion 20 is inserted into the hose 12, and the socket fitting 22 fixed by caulking to the outer peripheral surface of the hose 12 in this state is attached to the end of the hose 12. It is supposed to be fixed.
Here, the nipple fitting 14 has a large-diameter hexagonal tool hook 23, and an annular fixing groove 24 is formed at an adjacent position thereof. The fixing part 26 is inserted.

The adapter 16 has a female fitting portion 28.
A female tapered surface 30 is formed on the inner peripheral side of the distal end portion of the female fitting portion 28, and a male screw portion 32 is formed on the outer peripheral surface.
On the other hand, the nipple fitting 14 has a male fitting portion 34, and a male tapered surface 36 is formed on the outer peripheral side of the tip portion.

  Here, the female taper surface 30 and the male taper surface 36 basically have the same taper angle (angle formed with the axial direction). However, strictly speaking, the taper angle of the female taper surface 30 is set to an angle within a range of 0 to 30 ′ (minutes) with respect to 30 °, while the male taper surface 36 has a taper angle of 0 to −30 ′ (with respect to 30 °). The angle is within the range of minutes). That is, the taper angle of the male taper surface 36 is set to a small angle by a minute angle with respect to the taper angle of the female taper surface 30.

An annular locking groove 38 is formed on the outer peripheral surface of the male fitting portion 34 of the nipple fitting 14.
The other cap nut 18 is provided with an inward annular locking protrusion 40 at one end in the axial direction, and a hexagonal tool hook 42 having a large diameter at the other end in the axial direction. An internal thread portion 44 is formed on the inner peripheral surface of 42.
The tool hook 42 and the annular locking protrusion 40 are connected in the axial direction by a connecting portion 46 having a cylindrical shape.

In the hose joint 10, the female threaded portion 44 of the cap nut 18 is screwed into the male threaded portion 32 of the adapter 16 with the annular locking projection 40 of the cap nut 18 locked in the annular locking groove 38 of the nipple fitting 14. The nipple fitting 14 and the adapter 16 are fastened in the axial direction.
At this time, the male tapered surface 36 of the nipple fitting 14 and the female tapered surface 30 of the adapter 16 are pressed in the axial direction based on the screw fastening force by the cap nut 18, and the nipple fitting 14 and the adapter 16 are brought into contact with each other by metal contact. Metal seal.

FIG. 2 is an enlarged view of the adapter 16 and the nipple fitting 14 before being fastened. As shown in FIG. 2, in this embodiment, the sectional shape of the tip of the male tapered surface 36 of the nipple fitting 14 is shown. Is an arcuate curved surface. In the figure, 36A represents the tip curved portion.
In this embodiment, the curved surface at the tip curved portion 36A is an arc-shaped curved surface having a radius of 0.5 to 2.0 mm (preferably a radius of 0.7 to 1.6 mm, more preferably 0.7 to 1. 3 mm).

  Table 1 shows various changes in the radius of curvature of the curved surface of the distal end curved portion 36A of the male tapered surface 36, and the nipple fitting 14 and the adapter 16 are screwed together with the cap nut 18 with various tightening torques (however, here) Shows the result of investigating the presence or absence of leakage by applying a pressure of 27.4 MPa, which is a working pressure, to the inside for 1 minute.

Note that the tip corner portion 220A of the male tapered surface 220 in the conventional nipple fitting 204 cannot be a strict pin angle shape although it is a square shape (pin angle shape), and a minute curvature up to 0.3 mm (curvature radius). It has a curved surface shape with a radius.
Here, in order to make a comparison with this, a test was also conducted with a curvature radius of 0.3 mm.
In Table 1, the tightening torque 20 N · m corresponds to 15% of the standard tightening torque 132 N · m. 30 N · m corresponds to 23% of the standard tightening torque.

This test was carried out in order to investigate whether or not the sealing performance is lowered when the curvature radius R of the curved surface of the tip curved portion 36A of the male tapered surface 36 is increased. As shown in the results, when the curvature radius R becomes larger than a certain value, specifically, when the curvature radius R becomes 1.5 mm or more, leakage occurs under a tightening torque of 20 N · m.
However, such leakage was confirmed when the cap nut 18 was tightened under a low tightening torque 20 N · m corresponding to 15% of the standard tightening torque 132 N · m. Such a leak does not occur under m.

Therefore, when the leakage occurs under each radius of curvature in order to investigate the pressure at which the leakage occurred under the tightening torque of 20 N · m, that is, to investigate the pressure resistance under the tightening torque. The pressure of was examined.
It should be noted that, here, a test for obtaining a pressure resistance was performed for those having curvature radii of 0.3, 0.5, and 1.0 mm in which leakage did not occur when a pressure of 27.4 MPa was applied in the results of Table 1. ing.
The results are shown in Table 2.

  As shown in the results of Table 2, it has been found that the pressure resistance tends to decrease as the radius of curvature increases.

  As described above, the pressure resistance decreases as the tip of the male tapered surface 36 is curved and the radius of curvature of the curved surface is increased. The reason why the male tapered surface 36 with respect to the female tapered surface 30 increases as the radius of curvature increases. This is considered to be due to the fact that the degree of biting at the tip is reduced and the surface pressure at the contact portion is reduced.

FIG. 3 specifically shows this.
As shown in FIGS. 3B and 3B, the tip of the male tapered surface 220 is a tip corner portion 220A having a pin corner shape (substantially a curved surface having a radius of curvature up to a maximum of 0.3 mm). The force due to tightening of the cap nut acts on the tip corner 220A intensively and greatly, and the tip corner 220A bites into the female taper surface 214 while being partially crushed, thereby increasing the surface pressure. In addition, sealing performance, that is, pressure resistance can be obtained (at this time, the male tapered surface 220 and the female tapered surface 214 are in linear contact at the tip corner portion 220A in the pin angle state), on the other hand, as shown in FIG. As shown, if the tip of the male taper surface 36 is a curved tip curved portion 36A and the radius of curvature is large, the biting by the tip curved portion 36A is weakened and the force by tightening the cap nut 18 is one point (strictly Is around Without concentrating in a linear manner), and as a result, the surface pressure at the contact portion between the tip curved portion 36A and the female taper surface 30 decreases, and this increases the sealing performance, that is, as the radius of curvature increases. It is considered that the pressure resistance shows a decreasing tendency.

However, leakage occurs in Table 2 when tightening is performed under a low tightening torque of 20 N · m. When the standard tightening torque is 132 N · m, the radius of curvature is 0.5. None of 1, 1.5, and 2 mm leaks, and therefore, as long as tightening is performed with a specified standard tightening torque, there is no problem.
Next, the following test was performed on the sealing performance when tightening was performed in a state where lateral force in the direction perpendicular to the axis was applied.

Specifically, this test was performed as follows.
That is, as shown in FIG. 4, the nipple fitting 14 is fixed to the end of the hose (hose inner diameter: φ19 mm) 12 while the holder 16 is fixed by a pair of clamping jigs 48-1 and 48-2. In this state, the cap nut 18 is first lightly fitted to the male threaded portion 32 of the holder 16, and the string tied to the hose 12 at a position 50 mm away from the socket fitting 22 is pulled in the lateral direction (perpendicular to the axis). Then, lateral forces in the direction perpendicular to the axis shown in Table 3 are applied to the nipple fitting 14 via the hose 12, and the cap nut 18 is tightened with a constant tightening torque of 140 N · m in this state, and then the socket fitting 22 On the other hand, impact was applied with a spanner from four directions separated by 90 ° in the circumferential direction, and vibrations were applied to the screw fastening portion, and then the removal torque of the cap nut 18 was measured.

In other words, with the lateral force F applied, the cap nut 18 is tightened under a constant tightening torque of 140 N · m, and after applying an impact from the lateral direction, the cap nut 18 is unfastened. The removal torque at the time was obtained.
The results are shown in Table 3 and FIGS.

As shown in these results, when the curvature radius is 0.3 mm, when the lateral force F is not applied, the removal torque is large, and good sealing performance is exhibited. As the force F increases, the removal torque decreases significantly.
On the other hand, by increasing the radius of curvature R, a good removal torque, that is, a good sealing property can be obtained even when tightening is performed with a lateral force F applied.

Specifically, when the lateral force F is 300 N, the removal torque is remarkably reduced to 31 N when the curvature radius is 0.3 mm. However, when the curvature radius is 0.5, 1, 1.5, and 2 mm, the curvature radius is 0. . High removal torque value compared to 3 mm.
Therefore, it is desirable that the curvature radius of the tip curved portion 36A be 0.5 mm or more.

However, when the curvature radius R is increased, the maximum value is exhibited at a certain point, and thereafter, the removal torque tends to decrease as the curvature radius increases.
This tendency becomes more prominent as the lateral force F increases.
For example, in the case of a lateral force of 300 N, as shown in FIG. 5, when the radius of curvature exceeds 2 mm, the tightening torque tends to decrease rapidly.
Therefore, it is desirable to keep the radius of curvature within 2.0 mm at the maximum.

In these results, a good value is shown when the radius of curvature is in the range of 0.7 to 1.6 mm (removal torque is over 80 N · m under lateral force of 300 N). The case where the radius of curvature is 1 mm is particularly desirable.
However, it is desirable to set the radius of curvature so that the actual curvature is within the range of 0.7 to 1.3 mm in consideration of an error of about ± 0.3 mm in manufacturing.

  According to the present embodiment as described above, even when the nipple fitting 14 and the adapter 16 are fastened with the cap nut 18 in a state where a lateral force in a direction perpendicular to the axis is applied, the bent end portion of the male tapered surface 36 is obtained. It is possible to prevent 36A from partially biting into the female tapered surface 30, and even if the tip curved portion 36A is temporarily brought into contact with the female tapered surface 30, it is further increased. By tightening the cap nut 18, the inclination of the male tapered surface 36 with respect to the female tapered surface 30 is naturally corrected by the guiding action of the curved end portion 36A with the R shape, and the distal curved portion 36A is uniformly female over the entire circumference. The taper surface 30 can be brought into pressure contact, and a stable and good sealing state can be revealed.

  Further, by setting the radius of curvature of the tip curved portion 36A to a certain value or less, the force due to the tightening of the cap nut 18 is excessively dispersed, leading to a decrease in surface pressure, which leads to a decrease in sealing performance. The problem can be avoided well.

Although the embodiment of the present invention has been described in detail above, this is merely an example.
For example, in the above embodiment, a male taper surface is formed on the nipple fitting 14 side and a female taper surface is formed on the adapter 16 side. However, in the present invention, the male taper surface is formed on the adapter 16 side and the nipple fitting 14 is fitted. It is also possible to apply to a hose joint in which a female taper surface is formed on the side, and for a hose joint in which a male pipe and a female pipe of a form or type different from the above example are fastened with a cap nut However, the present invention can be applied in various forms without departing from the gist of the present invention.

It is a figure which shows the hose coupling of one Embodiment of this invention. It is the figure which expanded and showed the principal part of FIG. 1 in the state before a joint fastening. It is the figure which showed the principal part shown in FIG. 2 together with the comparative example in the joint fastening state. It is explanatory drawing of the test method for confirming the effect of this embodiment. It is a figure showing the relationship between the curvature radius of the front-end | tip curved part of a male taper surface, and removal torque. It is a figure showing the relationship between the magnitude | size of lateral force and the removal torque. It is a figure which shows an example of the conventional hose coupling. It is explanatory drawing showing the state fastened in the state which the hose bent in FIG. It is explanatory drawing of the malfunction which arises in the hose coupling of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Hose coupling 14 Nipple metal fitting 16 Adapter 18 Cap nut 30 Female taper surface 32 Male thread part 36 Male taper surface 36A Tip curved part 38 Annular latching groove 40 Annular latching protrusion 44 Female thread part

Claims (2)

(B) a metal female tube having a female tapered surface on the inner peripheral side; (b) a metal male tube having a male tapered surface having a taper angle smaller than the female tapered surface on the outer peripheral side; One of the male pipe and the female pipe is provided with an inward annular locking projection that is locked in an annular locking groove formed on the outer circumferential side of one of the male pipe and the female pipe, and is formed on the other outer circumferential surface. A cap nut having a female screw portion screwed to the male screw portion at the other end in the axial direction, and the male taper surface is turned into the female taper surface by screwing the cap nut into the male screw portion. In a hose joint that connects the hose and the counterpart device side by fastening the male pipe and the female pipe in a sealed state with a metal seal due to contact between the metals by pressure contact,
A hose coupling characterized in that the cross-sectional shape of the tip of the male tapered surface is an arc-shaped curved surface having a radius of 0.5 to 2.0 mm over the entire circumference.   The hose joint according to claim 1, wherein the curved surface shape is an arc shape having a radius of 0.7 to 1.3 mm.

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