JPH0687795U - Pipe fitting - Google Patents

Abstract

(57) [Abstract] [Purpose] A cap nut rotatably fitted to the tip of the first tube body so as not to come off from the tip, and a second nut.
And a hollow bolt fitted and fixed to the tip of the tubular body of the first embodiment, and the cap nut and the hollow bolt are screwed together to form a first bolt.
For the pipe joint connecting the second pipe and the second pipe, the second pipe and the hollow bolt are fixed so that relative displacement does not occur due to an external force unavoidably applied during and after the pipe connection, and after the pipe connection. The airtightness with respect to the internal pressure can be stably secured. [Constitution] On the inner peripheral surface of the hollow bolt (4) near the rear end,
A plurality of engaging grooves (4a) parallel to the axial center are provided at intervals in the circumferential direction, while at the outer peripheral surface of the root part of the tip part fitted in the hollow bolt (4) of the second tubular body (3). , A movement preventing projection (3a) which engages with the engaging groove (4a) of the hollow bolt (4) is provided, and the movement preventing projection (3a) and the engaging groove (4a) are engaged with each other. To fix.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a pipe joint used for piping such as a refrigerant circuit and a hydraulic circuit.

[0002]

[Prior art]

 As is well known, in order to connect rubber hoses and flexible hoses used for piping of refrigerant circuits of air conditioners and hydraulic circuits of hydraulic equipment to each other or to other equipment, connect them to the hose end and the other equipment. A method is generally adopted in which a pair of pipe joints are connected to each other and detachably connected to each other through the pipe joints.

FIG. 4 shows an example of a conventional pipe joint of this type. In the pipe joint shown in the figure, the tip of the first pipe body (21) is inserted into the cap nut (22), and bulge molding is added to the tip of the cap nut to provide the cap nut (22) at the rear. An annular bulge (21a) that engages with the reduced diameter step (22a) is formed, and the cap nut (22) is rotatably integrated so that it does not come off from the tip of the pipe (21). To form a female pipe joint, insert the tip of the second pipe (23) into the hollow bolt (24), and apply pressure from the inside to the tip to make it hollow. Make sure that the hollow bolt (24) does not come off from the tip of the pipe (23) by making sure that the hollow bolt (24) does not come off from the tip of the tubular body (23) by closely contacting it with the expanded diameter hole (24a) provided at the front of the bolt (24). A male pipe joint, in which the first pipe body (21) and the second pipe body (23) are detachably connected by screwing the cap nut (22) and the hollow bolt (24) together. Has been done. Normally, when both are connected, an O-ring (25) is formed between the front end face of the annular bulging portion (22a) of the first pipe body (21) and the tip of the second pipe body (23). ) Is inserted, which maintains the airtightness between the two. Further, in such a pipe joint, a pipe made of Al or an Al alloy, which is lightweight and excellent in workability, is widely used as the pipe body, and the rear end of the pipe body is the end portion of the hose for piping. Or it is stuck to the other device.

In addition, there are two types of pipe joints of this form: a hollow bolt that is loosely fitted on the pipe body and is rotatable, and a pipe joint that is fixed by brazing or the like.

In the former case, as shown in FIG. 5, for example, on the outer peripheral surface of the root portion of the second pipe body (23) inserted into the hollow bolt (24) and on the rear surface of the hollow bolt (24). A pipe joint provided with a rear movement preventing projection (23a) that abuts has been proposed (Japanese Utility Model Publication No. 2-1588) and has been put to practical use. In this conventional pipe joint, the backward movement of the hollow bolt (24) is blocked by the rearward movement preventing projection (24b), so that it is not necessary to screw it into the mating cap nut (22) at the initial stage. The screwing work can be done with one hand.

However, in this conventional pipe joint (Jpn. Pat. Appln. KOKAI Publication No. 2-1588), both the cap nut (22) and the hollow bolt (24) rotate, so it is light at the initial stage (2 to 3 pitches). The screwing work can be done with one hand, but if you try to screw in more than that, the other party will start to rotate, resulting in the need to tighten many pitches at the same time with a spanner, etc. Since it is fixed, it is disadvantageous in terms of workability during piping compared to the latter pipe joint where only the final stage needs to be tightened at the same time with a wrench or the like.

On the other hand, in the latter pipe joint, workability at the time of piping is better than that of the former pipe joint, but in order to join the pipe body and the hollow bolt by brazing, cleaning treatment of the surface of the joint portion, Many processes such as brazing, heat treatment after joining, and cleaning treatment for flux removal are required, which raises a problem of increasing manufacturing cost.

Therefore, studies have been made to solve this problem. For example, as shown in FIG. 6, (a) is a longitudinal sectional view, (b) is a sectional view taken along line AA of (a). Cross-sectional view), a plurality of bulging portions (23b) are arranged at intervals in the circumferential direction on the outer peripheral surface of the root portion of the tip of the second tubular body (23) inserted into the hollow bolt (24). The outer end surface of the hollow bolt (24) is pressed against the inner peripheral surface of the hollow bolt (24), so that the hollow bolt (24) can be fixed to the second tube (23) without depending on brazing. The following pipe joint has been proposed (Japanese Utility Model Laid-Open No. 1-154389). In this conventional pipe joint, the hollow bolt is fixed by locally forming a bulge on the tip of the pipe, so the fixing work is simple and the hollow bolt is fixed to the pipe. This facilitates piping work.

[0009]

[Problems to be solved by the device]

 By the way, in the pipe joint having the above structure, as described above, the front end face of the annular bulging portion (22a) formed in the first pipe body (21) inserted into the cap nut (22) and the hollow bolt ( An O-ring (25) is interposed between the end of the second pipe body (23) that is in close contact with the expanded hole portion (24a) of (24), so that airtightness against internal pressure after piping is achieved. Is maintained.

Therefore, in order to secure the airtightness and prevent the internal pressure from leaking after the piping, the annular bulging portion (22a) of the first pipe body (21) and the second pipe body (22a) ( By improving the accuracy of the shape of the tip of 23) and the external force that is unavoidably applied during and after piping, the relative displacement between the first pipe body (21) and the second pipe body (23) It is important to improve the accuracy of combination of the pipes (21) and (23) with the cap nut (22) and the hollow bolt (24) so that they do not occur. Further, for that purpose, it is particularly important that the second pipe body (23) is brought into close contact with the inner surface of the hollow bolt (24) reliably and accurately. From this point of view, the hollow bolt is fixed to the pipe body as compared with the former pipe joint in which the hollow bolt is loosely fitted onto the pipe body and rotatable. The latter pipe fitting is much more advantageous.

However, the conventional pipe joint shown in FIG. 6 (Japanese Utility Model Laid-Open No. 1-154389) does not rely on brazing, which requires many steps, and fixes and integrates the hollow bolt and the pipe body. Although it is possible to improve the combined dimensional accuracy of both, if this is put into practice, the following problems will occur.

That is, in this conventional pipe joint, a plurality of bulges that press the inner peripheral surface of the hollow bolt (24) on the outer peripheral surface of the distal end portion of the second pipe body (23) by their respective outer surfaces. Since the hollow bolt (24) is fixed to the tip of the second pipe body (23) by forming the portion (23b), the fixing between the two is that the bulge of the pipe body (23) is fixed. Since it is achieved by the contact resistance between the outer surface of the part (23b) and the inner peripheral surface of the hollow bolt (24), the fixing force between the two can sufficiently oppose the external force that is unavoidably applied during and after piping. So hard to raise.

In particular, when an external force around the axis is applied to the second tubular body (23), relative sliding in the rotational direction easily occurs between the tubular body (23) and the hollow bolt (24). Also, once a relative slip in the rotating direction occurs, the adhesion force between the two tends to decrease sharply. Therefore, due to the external force applied during and after piping, the first pipe (21 ) And the second pipe (23) are displaced relative to each other, and as a result, the O-ring (5) interposed between them is displaced or deformed, resulting in airtightness against internal pressure. It is easy to cause the problem that Further, this tendency is particularly remarkable when a pipe made of Al or Al alloy having excellent workability is used as the tubular body.

The present invention has been made to solve the above-mentioned problems of the conventional technique, and the hollow bolt is relatively easily fixed to the second pipe body without depending on brazing or the like. The second pipe body and the hollow bolt are unavoidably provided during and after the pipe arrangement as well as the economical efficiency and the workability at the time of piping can be improved, and the combined dimensional accuracy of both can be improved. The purpose of the present invention is to provide a pipe joint that can be firmly fixed and integrated so that relative displacement does not occur due to an external force applied, and that can ensure airtightness against internal pressure after piping in a stable manner.

[0015]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention has the following configuration. That is, the pipe joint according to the present invention includes a cap nut (2) rotatably fitted to the tip of the first pipe (1) so as not to come off the tip, and a second pipe (2). 3) A hollow bolt (4) fitted and fixed to the tip end of the hollow pipe (4) is provided, and the cap nut (2) and the hollow bolt (4) are screwed together to form the first tubular body (1). In the pipe joint to which the second pipe body (3) is connected, the inner peripheral surface of the hollow bolt (4) near the rear end is provided with an engaging groove (4a) parallel to the axial center in the circumferential direction. A plurality of hollow bolts (4a) are provided on the outer peripheral surface of the root portion of the distal end of the second tubular body (3), which is fitted into the hollow bolt (4) of the second tubular body (3). It is characterized in that it is provided with a movement preventing projection (3a) which engages.

[0016]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. [Fig. 1] is a drawing showing the structure of a pipe joint of the first embodiment of the present invention, wherein (a) is a semi-longitudinal front view, (b) is a sectional view taken along the line AA of (a). , (C) is a sectional view taken along line BB of (a).

In FIG. 1, (1) is a first tube body, and this tube body (1) is made of a pipe made of Al alloy, and its tip is inserted into the cap nut (2). An annular bulge (1a) formed by bulge molding is formed at the tip of the bulge. The rear end of the pipe body (1) is fixed to a hose for piping or a counterpart device (not shown).

On the other hand, the cap nut (2) has an inner diameter slightly larger than the outer diameter of the main body of the first tube (1) at the rear of the main body having the female screw (2a) on the inner peripheral surface. It has a reduced diameter step portion (2b). Then, the reduced diameter stepped portion (2b) and the annular bulging portion (1a) of the tubular body (1) are engaged with each other so that the first tubular body (1) can be prevented from coming off and rotated. And is integrally combined with the first tube (1).

(3) is a second tubular body, and this tubular body (3) is made of the same Al alloy pipe as the first tubular body (1) and has a hollow bolt (4) at the tip. While being inserted into the hollow bolt (24), the front end of the hollow bolt (24) is pressed against the inner side of the hollow bolt (24) to be expanded and molded, and is closely fixed to the inner peripheral surface of the hollow bolt (24).

On the other hand, the hollow bolt (4) has an inner diameter slightly larger than the outer diameter of the main body portion of the second tubular body (1) on the inner peripheral surface of the hexagonal nut-shaped head, and Inside the main part with grooved holes (4b) in which four circumferentially parallel engaging grooves (4a) are provided at equal pitches in the circumferential direction, and male threads (4c) are provided on the outer peripheral surface. The peripheral surface has a diameter-expanded hole portion (4d) having a diameter larger than that of the grooved hole portion (4b) and having a diameter increased in two steps toward the tip. The engaging groove (4a) of the grooved hole portion (4b) is provided with a U-shaped cross-sectional shape over the entire axial length of the grooved hole portion (4b).

Further, the second tubular body (1) has a distal end portion into which the hollow bolt (4) is inserted into the diameter-expanding hole portion (4d) by press-expansion molding in advance. (4d) Preformed into a shape that fits the inner surface, then inserted into the hollow bolt (4), and in the main part of the hollow bolt (4), the diameter is slightly increased by a press-fitting die to increase the diameter of the expanded hole (4d). ) It is closely attached to the inner surface, that is, it is formed to have a larger diameter than the inner diameter of the grooved hole (4b), so that the hollow bolt (4) does not come off from the tip of the second pipe body (3). It is fixed as. Furthermore, in the head of the hollow bolt (4), the root part that has not been preformed is expanded and shaped by a press-fitting die so that it is brought into close contact with the inner surface of the grooved hole (4b) and its outer periphery. The surface is formed with movement preventing projections (3a) that engage with the four engaging grooves (4a) of the grooved hole portion (4b), respectively, and the movement preventing projections (3a) and the engaging grooves (4a) are formed. The engagement of the second tube body (3) and the hollow bolt (4) are fixed and integrated so as not to cause relative displacement in the rotational direction.

In this pipe joint, as shown in (a), the cap nut (2) and the hollow bolt (4) are screwed to each other so that the first pipe body (1) and the second pipe body are (3) Connect with. In addition, an O-ring (5) is interposed between the front end surface of the annular bulging portion (2a) of the first tube body (1) and the tip of the second tube body (3), which prevents internal pressure from increasing. Airtightness is maintained.

In the pipe joint of the present embodiment having the above-mentioned configuration, the hollow bolt can be fixed to the second pipe body without depending on brazing or the like, so that the economy and the workability during piping are improved. In addition to being improved, it becomes easy to improve the dimensional accuracy of the combination of both.

[0024] Further, since the movement preventing projection of the second pipe body and the engagement groove of the hollow bolt are firmly fixed to each other, they are relatively fixed during and after piping. It is able to withstand a large moment about the axis, which causes relative slippage between the first and second pipes, resulting in displacement and deformation of the inserted O-ring. It is possible to stably secure the airtightness against the internal pressure after piping.

FIG. 2 is a semi-longitudinal sectional front view showing the structure of the pipe joint of the second embodiment of the present invention. The pipe joint of the present embodiment is the same as that of the first embodiment except that the shape of the engaging groove of the hollow bolt is partly different. The explanation is omitted by attaching the reference symbols, and only the differences will be summarized and explained.

In the pipe joint of this embodiment shown in FIG. 2, at least one of the four engaging grooves (4a) provided on the inner peripheral surface of the grooved hole portion (4b) of the hollow bolt (4) is One or more engagement grooves (4a ') are not provided over the entire axial length of the grooved hole (4b), and a part of the inner side that is the main body side with the male screw (4c) is provided. It is blocked.

Then, in the same manner as in the first embodiment, the distal end portion of the second tubular body (1) is inserted into the hollow bolt (4) provided with the engaging groove (4a ′), and The tip of the hollow bolt (24) is expanded and molded with a press-fitting die to make it adhere and fix to the inner peripheral surface of the hollow bolt (24).

In the pipe joint of the present embodiment having the above-mentioned configuration, the closed portion inside the engagement groove (4a ′) is arranged in the axial direction of the movement preventing projection (3a) that engages with the engagement groove (4a ′). It becomes a protrusion that prevents movement. Therefore, in the pipe joint of the present embodiment, the second pipe body (3) and the hollow bolt (4) sufficiently oppose the external force that is unavoidably applied during and after the piping, and the second tubular body (3) and the hollow bolt (4) are prevented from rotating and axial directions. It can be securely fixed so that relative displacement does not occur.

Next, a method of fixing / integrating the second pipe body and the hollow bolt in the pipe joint of the above-described second embodiment will be described with reference to the schematic process explanatory diagram [FIG. 3]. .

First, a pipe body (3) is manufactured by cutting an Al alloy pipe into a predetermined length and chamfering both ends. The tubular body (3) at this point is just a straight tube as shown in Fig. (A).

Further, the hollow bolt (4) shown in FIG. 2 (b) is manufactured by a precision die forging method or the like. As described above, the hollow bolt (4) has four inner diameters in its head, which are slightly larger than the outer diameter of the tubular body (1) and whose inner peripheral surface is parallel to the axial center. In addition to having grooved holes (4b) with mating grooves (4a) arranged at equal pitches in the circumferential direction, and having a larger diameter than the grooved holes (4b) in the main body with external threads (4c) on the outer peripheral surface. And has a diameter-expanding hole portion (4d) whose diameter is expanded in two steps toward the tip. The engaging groove (4a) of the grooved hole portion (4b) had a U-shaped cross section, and was formed by machining in this example.

On the other hand, the diameter of the hollow bolt (4) is expanded at the tip of the tubular body (3) by press-expansion molding as shown in (c). Preform into a shape along the inner surface of the hole (4d).

Then, the preformed tube (3) is inserted from the main body side provided with the male screw (4c) of the hollow bolt (4) as shown in FIG. While holding the outer periphery of the part of the hollow bolt (4) near the head rear surface of (4) with a clamp type (C), press-fit it in a punch shape with its outer diameter changed from the front end side. Press in the die (D).

Then, the press-molding die (D) is press-fitted to slightly expand the diameter of the preformed portion of the tubular body (3), and as shown in FIG. While pressing and adhering, the unpreformed root part of the tubular body (3) located in the grooved hole (4b) of the head of the hollow bolt (4) is expanded and the groove is formed. Press it into close contact with the inner surface of the hole (4b). At this time, a part of the tube wall material of the tubular body (3) pressed against the inner surface of the grooved hole portion (4b) is partially engaged with the engaging groove (4a) provided on the inner peripheral surface of the grooved hole portion (4b). ) Inside the tube body (3), it flows into the inside of the pipe (3) by plastic flow, and as shown in Fig. (F), the movement prevention protrusions that engage with the four engaging grooves (4a) are formed on the outer peripheral surface of the root of the pipe body (3). The part (3a) is formed.

As described above, the second pipe body (3) and the hollow bolt (4) are fixed and integrated, but the pipe body (3) and the hollow bolt (4) are prevented from moving. Since the protrusion (3a) and the engagement groove (4a) are firmly fixed and integrated with each other, it is possible to obtain a fixing force that can sufficiently resist the inevitable external force applied during and after piping. . Further, as described above, the fixing and integration of the two can be achieved by a relatively simple procedure, and the press-fitting die (D) for press-fitting the fixing / integrating the tube body (3) and the hollow bolt ( 4) Combination with can improve dimensional accuracy.

The above-mentioned fixing / integrating method is an example, and the pipe joint of the present invention is not limited by this. For example, in the above example, the diameter expansion by the press-fitting die (D) to the preform part of the tubular body (3) was made small, but in general, the main part of the hollow bolt (4) was compared. Since it is formed to be relatively thin, the main part, that is, the male screw (4c) is deformed when a large pressure is applied from the inside by the press-fitting die (D). However, if it is necessary to set the pressing force from the inside by the press-fitting die (D) to be slightly higher in order to secure the close contact with the inner surface of the expanded diameter portion (4d), for example, (e) As shown by the alternate long and two short dashes line in the figure, the two-piece female screw inner cylinder that is screwed onto the male screw (4c) is provided on the main body part where the male screw (4c) of the hollow bolt (4) is provided. A back-up die (B) having (B1) can be arranged to prevent deformation due to the pressing force from the inside.

Further, by arranging the backup die (B) as described above, the straight pipe (3) which is not preformed is inserted into the hollow bolt (4) and the pipe ( 3) It is also possible to expand and shape the tip part in a single step by press-fitting with a press-fitting die (D), press it into close contact with the inner surface of the hollow bolt (4), and fix and integrate both.

Further, in the above-mentioned 2 examples, the tube body, the cap nut and the hollow bolt were made of Al alloy, but this is one example, and it is excellent in cold workability and has a required structural strength. It is needless to say that the material may be made of another metal material depending on its use and purpose as long as it can obtain.

[0039]

[Effect of device]

 As described above, the pipe joint according to the present invention can relatively easily fix the hollow bolt to the second pipe body without depending on brazing or the like, which is economical and economical. The workability at the time of piping is excellent and the dimensional accuracy of the combination of both can be improved, and the relative displacement between the second tubular body and the hollow bolt due to the external force unavoidably applied during and after the piping. It can be firmly fixed and integrated so that it does not occur, so that airtightness against internal pressure after piping can be stably secured.

[Brief description of drawings]

1A and 1B are views showing a structure of a pipe joint of a first embodiment of the present invention, in which FIG. 1A is a semi-longitudinal front view, and FIG.
-A sectional drawing, (c) figure is BB sectional drawing of (a) figure.

FIG. 2 is a semi-longitudinal sectional front view showing the structure of the pipe joint of the second embodiment of the present invention.

FIG. 3 is a schematic process explanatory view of a method of fixing and integrating a tubular body and a hollow bolt according to an embodiment of the present invention.

FIG. 4 is a sectional view showing a configuration of a conventional pipe joint.

FIG. 5 is a cross-sectional view showing the configuration of another conventional pipe joint.

FIG. 6 is a cross-sectional view showing the structure of another conventional pipe joint.

[Explanation of symbols]

 (1) --First tube (1a)-Annular bulge (2) --Cap nut (2a)-Female screw (2b)-Reduced diameter step (3) --Second Tube (3a)-Movement prevention protrusion (4)-Hollow bolt (4a)-Engaging groove (4b)-Grooved hole (4c)-Male screw (4d)-Expanded hole Part (5) --O-ring

Claims (1)

[Scope of utility model registration request] 1. A cap nut rotatably fitted to the tip of the first tube body (1) so as not to come off from the tip.
(2) and a hollow bolt (4) fitted and fixed to the tip of the second tubular body (3), and the cap nut (2) and the hollow bolt (4) are screwed together. The first tubular body
In a pipe joint in which (1) and the second pipe body (3) are connected,
On the inner peripheral surface of the hollow bolt (4) near the rear end, a plurality of engaging grooves (4a) parallel to the axial center are provided at intervals in the circumferential direction, and the second tube (3) On the outer peripheral surface of the root part of the tip part that is fitted in the hollow bolt (4), engage the groove of the hollow bolt (4).
A pipe joint provided with a movement preventing projection (3a) which engages with (4a).