Pipe joint

Abstract

To provide a pipe joint with a pipe not cut even when a flattening level with a caulking machine is high.SOLUTION: In a pipe joint for making an inner periphery of a pipe body into close contact with an outer periphery of a nipple by inserting the pipe body along the outer periphery of the nipple and pressing it by a pipe from outside, irregularity is formed on the outer periphery of the nipple. A line connecting its maximum height portion has almost the same diameter on a deep side in a pipe body insertion direction from a nipple tip on a front side in the pipe body insertion direction. The pipe has a smallest diameter at a deeper position than a position, at which one part on the front side in the pipe body insertion direction is opposed to the nipple tip, has the same diameter in a predetermined range to a deep side in the pipe body insertion direction from the deep side position having the smallest diameter, and has a first taper part whose diameter is gradually increased on a deeper side beyond the predetermined range.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a pipe joint used for connecting a hose made of a material vulnerable to tearing, such as a thermoplastic resin or a thermosetting resin. Specifically, the present invention relates to a pipe joint in which a pipe body is inserted along the outer peripheral surface of a nipple, and the inner peripheral surface of the pipe body is brought into close contact with the outer peripheral surface of the nipple by pressing it with a pipe from the outside.

Background Art

[0002] Conventionally, as a pipe joint of this type, for example, as shown in Patent Document 1, it is composed of two parts, a nipple and a pipe. After covering the target pipe with the pipe and inserting the nipple into the pipe, the pipe is crushed with a caulking machine to prevent the pipe from coming off or leaking. Patent Document 2 shows an example of a laminated pipe targeted by a pipe joint.

[0003]

Patent Document 1

Patent Document 2

[0004] As shown in FIG. 8, the pipe joint of Patent Document 1 is configured such that the pipe connection is achieved by caulking the pipe P while sandwiching the pipe H between the inner peripheral surface of the pipe P and the outer peripheral surface of the nipple N. As for the structure of the connection part, while the inner peripheral surface of the pipe P is horizontal, the outer peripheral surface of the nipple N has a thin tip N1 and a taper N2 attached to the back side.

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when the pipe P is clamped by the caulking machine, if the pipe H is clamped from a location where the gap between the nipple N and the pipe P is narrow, since the taper N2 is provided toward the nipple tip N1, the pipe H will move so as to be pushed out to the right side in the drawing. In the pipe H with such behavior, stress concentration occurs at the location of the nipple tip N1 and the location of the pipe tip P1, and the pipe H as a hose may break. In particular, since the laminated pipe as shown in Patent Document 2 uses silicone rubber that is weak against tearing, it is likely to break. In order to prevent breakage, it is necessary to adjust the caulking amount by the caulking machine to reduce the caulking amount. However, if the caulking amount is too small, liquid may intrude into the inner side of the pipe H at the nipple tip N1, and an unnecessary liquid pool may be generated at this location.

[0006] An object of the present invention is to address such problems and provide a pipe joint in which the pipe does not break even when the caulking amount by the caulking machine is increased.

Means for Solving the Problems

[0007] To achieve such an object, the present invention inserts a pipe body along the outer peripheral surface of a nipple, and from the outside, a pipe By caulking and plastically deforming In a pipe joint that makes the inner peripheral surface of the pipe body adhere to the outer peripheral surface of the nipple, the nipple has irregularities formed on its outer peripheral surface, and a line connecting the maximum height portions thereof has a substantially the same diameter from the nipple tip on the front side in the pipe body insertion direction to the back side in the pipe body insertion direction , it is configured without providing a tapered shape in which the tip side is thin and becomes thicker toward the back side and is made to be so, and the pipe has a minimum diameter at a position deeper than the position where a part on the front side in the pipe body insertion direction faces the nipple tip, and has the same diameter over a predetermined range from the deeper position where the minimum diameter is reached to the back side in the pipe body insertion direction, and has a first tapered portion that gradually expands in diameter further deeper beyond the predetermined range.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0009] FIG. 1 is an explanatory view showing the overall configuration of the pipe joint according to an embodiment of the present invention, showing the state before the pipe body is inserted and clamped. FIG. 1(a) is a front view, FIG. 1(b) is a sectional view taken along line A-A of FIG. 1(a), and FIG. 1(c) is a perspective view. FIG. 2 is an explanatory view showing the overall configuration of the pipe joint according to an embodiment of the present invention, showing the state after the pipe body is inserted and clamped. FIG. 2(a) is a front view, FIG. 2(b) is a sectional view taken along line A-A of FIG. 2(a), and FIG. 2(c) is a perspective view.

[0010] As shown in FIGS. 1 and 2, the pipe joint 100 according to the embodiment of the present invention inserts and clamps the connecting side end portion of the pipe H in a state where the pipe 2 is covered along the outer peripheral surface of the nipple 1, so that the connecting side end portion of the pipe H is sandwiched in the radial direction between the outer peripheral surface of the nipple 1 and the inner peripheral surface of the pipe 2, whereby the inner peripheral surface of the pipe H is brought into close contact with and connected to the outer peripheral surface of the nipple 1.

[0011] FIG. 3 is an explanatory view showing the nipple of the pipe joint according to the embodiment of the present invention. FIG. 3(a) is a front view, and FIG. 3(b) is a sectional view taken along line A-A of FIG. 3(a).

[0012] As shown in FIG. 3, a plurality of unevennesses 11 are continuously provided in the axial direction or a plurality of unevennesses 11 are provided at appropriate intervals on the outer peripheral surface of the nipple 1. The line connecting the maximum height portions is made to have substantially the same diameter from the nipple tip 12 on the front side in the pipe body insertion direction to the back side in the pipe body insertion direction. The portion on the back side in the pipe body insertion direction from the plurality of unevennesses 11 having substantially the same diameter may be made into a smooth shape and may have a shape slightly smaller in outer diameter than the outer diameter of the unevennesses 11. In this case, it becomes easier to set the hose. Also, in the drawing, the unevennesses 11 are in a mode where a symmetric shape is repeated in order, but the plurality of protrusions may have a shape like a bamboo shoot that forms an acute top with a locking surface that stands up at a substantially right angle or an angle close to it with respect to the axis and an inclined surface that gradually decreases in diameter toward the tip side.

[0013] In the conventional example, there is no taper provided to facilitate the insertion of the hose, that is, a taper shape in which the tip side of the outer peripheral surface of the nipple is thin and becomes thicker toward the back side is not provided. Further, on the base end side in the axial direction of the nipple 1, a connecting portion 13 for connection to other machines is integrally provided, but its shape is not limited to the one shown in the drawing.

[0014] FIG. 4 is an explanatory view showing a pipe of the pipe joint according to an embodiment of the present invention, FIG. 4(a) is a front view before caulking, FIG. 4(b) is a cross-sectional view taken along line A-A of FIG. 4(a), FIG. 4(c) is a front view after caulking, and FIG. 4(d) is a cross-sectional view taken along line A-A of FIG. 4(c).

[0015] As shown in FIGS. 4(b) and 4(d), the inner peripheral surface of the pipe 2 has a minimum diameter at a position deeper than the position where a part on the front side in the pipe insertion direction faces the nipple tip 12 (see also FIGS. 5(b) and 5(d)). From the deeper position where the minimum diameter is obtained to the deeper side in the pipe insertion direction, the diameter is the same, that is, the minimum diameter, over a predetermined range 21.

[0016] On the further deeper side beyond the predetermined range 21, a first tapered portion 22 that expands in diameter toward the deeper side is provided. In the first tapered portion 22, a plurality of concavities and convexities are continuously provided in the axial direction or a plurality of them are provided at appropriate intervals. Further, from the deeper position where the minimum diameter is obtained to the front side, a second tapered portion 23 that expands in diameter toward the front side is provided. However, it is also possible to adopt a stepped shape in which the diameter suddenly increases from the deeper position where the minimum diameter is obtained. In order to prevent the pipe from breaking, more importantly, a part on the front side in the pipe insertion direction of the inner peripheral surface of the pipe 2 has a minimum diameter at a position deeper than the position where it faces the nipple tip 12.

[0017] As the material of the pipe 2, it is formed of a rigid material such as stainless steel or aluminum that undergoes compressive deformation under radial pressure by the caulking machine but does not undergo restoration deformation under the repulsive force from the pipe H. As shown in FIG. 2, which is an explanatory diagram showing the state after the pipe body is inserted and caulked, when the outer periphery of the pipe 2 is pressed outward in the central direction, the position of the tip with the minimum diameter is extended so as to coincide with the position of the nipple tip. In addition, the unevenness continuously provided in plurality on the first tapered portion 22 of the inner peripheral surface of the pipe 2 and the unevenness 11 continuously provided in plurality on the outer peripheral surface of the nipple 1 are arranged so that the positions of the respective unevenness engage alternately, and by sandwiching the pipe H, a high pulling force can be maintained.

[0018] The pipe H is made of a thermoplastic resin or a thermosetting resin. As the thermoplastic resin, general-purpose plastics such as polyvinyl chloride, polyolefin, polyurethane, and polyamide, engineering plastics having heat resistance of 100°C or higher, and super engineering plastics having heat resistance of generally 150°C or higher are used. As the thermosetting resin, silicone rubber and other rubbers are appropriately adopted according to the application. Also, like the technique described in Patent Document 2, it can be configured as a laminated pipe in which different materials with a fluororesin inner layer and a silicone rubber outer layer are adhered via a reinforcing thread made of synthetic resin fibers such as polyester. In this case, since the silicone rubber is a material weak against tearing and the fluororesin has flexibility, it is necessary to form a thin wall thickness and the tear resistance is inferior, but by combining it with this pipe joint, it becomes possible to prevent the pipe H from breaking.

[0019] Next, a method for connecting the pipe H by such a pipe joint 100 will be described according to its assembly procedure. First, cover the pipe 2 shown in FIG. 4 on the outer peripheral surface of the pipe H. Next, insert the nipple 1 shown in FIG. 3 into the pipe H covered with the pipe 2. Of course, depending on the operator's sense, first, insert the nipple 1 shown in FIG. 3 into the pipe H, and then cover the pipe 2 shown in FIG. 4 on the pipe H with the nipple 1 inserted. Since there is a certain clearance between the pipe 1 before caulking, the operation may be performed in an order that is easy for the operator to handle.

[0020] After the nipple 1, the pipe H, and the pipe 2 are arranged in this order from the inside to the outside, the pipe 2 is pressed by a caulking machine. In FIG. 6, the caulking machine S is a so-called octagonal caulking machine, and is configured to caulk eight locations on the outer peripheral surface of the pipe 2 with the same pressure by eight claws S1 called dies. By sandwiching the connecting side end portion of the pipe H between the outer peripheral surface of the nipple 1 and the inner peripheral surface of the pipe 2 in the radial direction, the inner peripheral surface of the pipe H is brought into close contact with the outer peripheral surface of the nipple 1 and the connection is completed.

[0021] The reason why the pipe joint 100 according to the embodiment of the present invention is less likely to break the pipe than the conventional pipe joint will be described with reference to FIG. 7. FIG. 7(a) shows a conventional example, and FIG. 7(b) shows the pipe joint 100 according to the embodiment of the present invention. Both are enlarged views showing an enlarged upper portion where the nipple, the hose, and the pipe overlap.

[0022] The nipple in the conventional pipe joint is provided with a taper as shown in FIG. 7(a) to facilitate the insertion of the hose. However, due to this taper, when the pipe P is caulked with a caulking machine, if the pipe H is tightened from a location where the gap between the nipple N and the pipe P is narrow, the pipe H will move so as to be pushed out to the right along the thick arrow shown. In the pipe H with such behavior, the hose-like pipe H may break due to stress concentration generated when the thickened pipe H by the movement is strongly pressed against the location of the nipple tip N1 or the pipe tip P1.

[0023] On the one hand, in the pipe joint 100 according to the embodiment of the present invention, the nipple 1 is not provided with a taper, while the pipe 2 is provided with a taper. As shown in FIG. 7(b), the pipe 2 has a minimum diameter at a position deeper than the position facing the nipple tip 12, and has the same diameter over a predetermined range 21 from the deeper position where the minimum diameter is reached to the deeper side in the pipe insertion direction. The pipe 2 is configured to have a first tapered portion whose diameter gradually increases on the further deeper side beyond the predetermined range 21. Further, the pipe 2 is also configured to have a second tapered portion whose diameter gradually increases from the deeper position where the minimum diameter is reached to the front side. Therefore, as shown in the drawing, the pipe H is pushed out and moves to both the left and right sides starting from the predetermined range 21. Accordingly, the wall thickness of the pipe H that is pressed against the nipple tip 12 becomes smaller than that in the conventional example. Furthermore, since the pipe H that moves by the second tapered portion does not escape upward in the drawing, stress concentration does not occur at the nipple tip 12. Also, the stress concentration generated at the tip of the pipe 2 becomes small enough not to cause a problem.

Example

[0024] Hereinafter, examples of the present invention will be described. [Examples 1, 2 and Comparative Examples 1, 2] Examples 1 and 2 and Comparative Examples 1 and 2 shown in Table 1 have a three-layer structure of an inner layer that becomes the innermost layer, a reinforcing layer formed by braiding reinforcing yarns, and an outer layer according to the materials described therein. And evaluation samples of the same size were produced respectively. In Examples 1 and Comparative Example 1, the target pipe H has a composition in which the inner layer is silicone rubber, and the outer layer is silicone rubber through a reinforcing layer made of polyester reinforcing yarn. In Examples 2 and Comparative Example 2, the target pipe H has a composition in which the inner layer is fluororesin ETFE, and the outer layer is silicone rubber through a reinforcing layer made of polyester reinforcing yarn. The pipe joints used in Comparative Examples 1 and 2 are conventional pipe joints with a taper towards the nipple tip, and the pipe joints used in Examples 1 and 2 are pipe joints according to the embodiment of the present invention.

[0025] [Evaluation Criteria] The "hydrostatic pressure test", "bending test", "liquid pooling test", and "comprehensive evaluation" shown in Table 1 are based on the following criteria. For the "hydrostatic pressure test", Examples 1 and 2 and Comparative Examples 1 and 2 were connected to a hydrostatic pressure tester, and a hydrostatic pressure that is a multiple of the normal pressure (water temperature 23°C: 0.5 MPa) was applied to each evaluation sample for a certain period of time (3 minutes), and the hydrostatic pressure at which each evaluation sample ruptured was measured. The test results were evaluated in three levels. In the evaluation results of this "hydrostatic pressure test", ◎: no rupture or water leakage even at 3 times or more of the normal pressure, ○: rupture or water leakage at 2 times the normal pressure, ×: rupture or water leakage at the normal pressure (1 time), were evaluated as such. For the "bending test", a continuous bending test with fittings was performed using Examples 1 and 2 and Comparative Examples 1 and 2 to confirm whether a cut occurs in either the inner layer or the outer layer. The test results were evaluated in three levels. In the evaluation results of this "bending test", ○: no cut, △: signs of a cut, ×: a cut occurred, were evaluated as such. Here, the continuous bending test with fittings is a test for comparing the bending performance and pressure resistance performance of each evaluation sample. Specifically, a fitting (pressure-resistant nipple) was inserted into and blocked the open end of each evaluation sample, the open end of the other end of each evaluation sample was blocked, and a load (2 Kg) was attached and supported in a substantially vertical state. Air at a predetermined pressure was intermittently supplied into each evaluation sample to make it in an air hammer state, and the side of the fitting (pressure-resistant nipple) was bent about 90 degrees to the left and right from the vertical state every certain period of time and repeated (20,000 times) for head shaking, and the state change of each evaluation sample was observed. Here, the test results were evaluated in three levels using Examples 1 and 2 and Comparative Examples 1 and 2. For the "liquid pooling test", the pipe joints of each evaluation sample were blocked using Examples 1 and 2 and Comparative Examples 1 and 2, colored ink was put in from the open end of the other end of each evaluation sample, the open end of the other end was blocked, and air at the normal pressure was intermittently supplied and pressurized for 24 hours. Then, after removing the ink and drying, it was cut and disassembled, and the state change of the ink intrusion into the clamped part of the pipe of the pipe joint, etc., was observed. The test results were evaluated in three levels. In the evaluation results of this "pooling test", it was evaluated in three grades: ○: no ink intrusion, △: signs of ink intrusion, ×: ink intrusion occurred. The "comprehensive evaluation" was comprehensively evaluated in three grades based on the evaluation results of the above-mentioned "hydrostatic pressure test", "bending test", and "pooling test". In the evaluation results of this "comprehensive evaluation", it was evaluated as ◎: best, ○: good, ×: unsuitable.

[0026]

Table 1

[0027] Thus, by adopting the shape of the pipe joint 100 according to the embodiment of the present invention, the elongation of the pipe H can be suppressed inside the pipe 2, and the hose discharge amount from the tip of the pipe 2 can be reduced. Therefore, stress concentration does not occur, and even if the clamping amount is increased, it is possible to effectively prevent the pipe H from breaking. And since the clamping amount can be increased, it is also possible to prevent the pooling of liquid that penetrates into the inside of the pipe H at the tip N1 of the nipple.

[0028] As described above, the pipe body having the wear detection function according to the embodiment of the present invention has been described in detail with reference to the drawings and its structure has been explained. However, the specific configuration is not limited to these embodiments, and design changes and the like within the scope not departing from the gist of the present invention are also included in the present invention. For example, in order to prevent the pipe from breaking, it is important that a part of the inner peripheral surface of the pipe 2 on the front side in the pipe body insertion direction is made to have the minimum diameter at a position deeper than the position facing the nipple tip 12. That is, even if a stepped portion is formed instead of the second tapered portion, it can be expected that the pipe joint will exhibit the intended function. However, being tapered is advantageous in that the movement of the hose becomes smoother.

Explanation of reference numerals

[0029] 1 Nipple 11 Concavo-convex 12 Nipple tip 13 Connection part 2 Pipe 21 Predetermined range 22 First tapered part 23 Second tapered part 100 Pipe joint H Pipe S Crimper S1 Claw (die)

Claims

1. In a pipe fitting, a pipe is inserted along the outer circumferential surface of a nipple, and the pipe is crimped from the outside to cause plastic deformation, so that the inner circumferential surface of the pipe is tightly fitted to the outer circumferential surface of the nipple. The nipple has an outer peripheral surface with projections and recesses, and a line connecting the maximum heights has a substantially constant diameter from the nipple tip on the front side in the tube insertion direction to the rear side in the tube insertion direction, and is configured without a tapered shape that is narrow at the tip and thickens toward the rear side. The pipe has a first taper portion in which a portion on the front side in the pipe insertion direction is made to have a minimum diameter at a position on the rear side relative to a position facing the nipple tip, and the diameter is constant over a predetermined range from the rear side position where the diameter is minimum to the rear side in the pipe insertion direction, and the diameter gradually increases further beyond the predetermined range. A pipe joint characterized in that

2. The pipe has a second tapered portion that gradually increases in diameter from the rear position where the diameter is smallest toward the front side.

2. The pipe joint according to claim 1 .

3. 3. The pipe joint according to claim 2, wherein when the outer periphery of the pipe is pressed from the outside toward the center, the position of the tip where the diameter is smallest coincides with the position of the tip of the nipple.

4. The pipe has a first tapered portion having projections and recesses.

3. A pipe joint according to claim 1 or 2.

Images