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 hoses made of a material that is weak against tearing, such as a thermoplastic resin or a thermosetting resin. More specifically, the present invention relates to a pipe fitting in which a tube is inserted along the outer circumferential surface of a nipple and then pressed from the outside with a pipe to bring the inner circumferential surface of the tube into tight contact with the outer circumferential surface of the nipple. [Background technology]

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

[0003] [Patent Document 1] JP 2006-220186 A [Patent Document 2] Patent No. 6814485

[0004] 8, the pipe fitting of Patent Document 1 is configured to connect pipes by clamping a pipe H between the inner peripheral surface of a pipe P and the outer peripheral surface of a nipple N and then crimping the pipe P. The structure of the connection part is such that the inner peripheral surface of the pipe P is horizontal, while the outer peripheral surface of the nipple N is narrow at the nipple tip N1 and has a taper N2 on the inner side. Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the pipe P is crimped with a crimping machine, if the pipe H is crimped from the narrow gap between the nipple N and the pipe P, the pipe H will move as if it is pushed to the right side in the figure because the taper N2 is provided toward the nipple tip N1. In the pipe H with such behavior, stress concentration occurs at the nipple tip N1 and the pipe tip P1, and the pipe H as a hose may break. In particular, the laminated pipe shown in Patent Document 2 is prone to breakage because it uses silicone rubber that is weak against tearing. In order to prevent breakage, it is necessary to adjust the amount of crushing by the crimping machine to reduce the amount of crushing. However, if the amount of crushing is too small, liquid will enter the inside of the pipe H at the nipple tip N1, and unnecessary liquid pools may occur at this location.

[0006] The present invention is intended to address such problems and has as its object to provide a pipe joint in which the pipe will not break even if the amount of crushing by the crimping machine is increased. [Means for solving the problem]

[0007] In order to achieve this object, the present invention provides a pipe fitting in which a tube is inserted along the outer peripheral surface of a nipple and pressed from the outside with a pipe to bring the inner peripheral surface of the tube into close contact with the outer peripheral surface of the nipple, the nipple having an uneven outer surface and a line connecting its maximum height parts having approximately the same diameter from the tip of the nipple on the front side in the tube insertion direction to the rear side in the tube insertion direction, the pipe having a minimum diameter at a part on the front side in the tube insertion direction further rear than the position facing the tip of the nipple, the pipe having a constant diameter over a predetermined range from the rear position at the minimum diameter to the rear side in the tube insertion direction, and having a first taper section which gradually increases in diameter further rearward beyond the predetermined range. [Brief description of the drawings]

[0008] [Figure 1]1A is a front view of a pipe fitting according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line AA of FIG. 1A. FIG. 1C is a perspective view of the pipe fitting according to an embodiment of the present invention. [Diagram 2] 2A is a front view of the pipe fitting according to an embodiment of the present invention, FIG. 2B is a cross-sectional view taken along line AA in FIG. 2A, and FIG. 2C is a perspective view showing the overall configuration of the pipe fitting according to an embodiment of the present invention after a pipe body has been inserted and tightened. [Diagram 3] 3A and 3B are explanatory views showing a nipple of a pipe fitting according to an embodiment of the present invention, in which FIG. 3A is a front view and FIG. 3B is a cross-sectional view taken along line AA of FIG. 3A. [Figure 4] 4(a) is a front view before crimping, FIG. 4(b) is a cross-sectional view taken along line AA in FIG. 4(a), FIG. 4(c) is a front view after crimping, and FIG. 4(d) is a cross-sectional view taken along line AA in FIG. 4(c). [Diagram 5] 5(a) is a front view before crimping, FIG. 5(b) is a cross-sectional view taken along line AA in FIG. 5(a), FIG. 5(c) is a front view after crimping, and FIG. 5(d) is a cross-sectional view taken along line AA in FIG. 5(c). [Figure 6] 6A, 6B, 6C, and 6D are diagrams for explaining a crimping machine, in which FIG. 6A is a front view, FIG. 6B is a left side view, FIG. 6C is a right side view, and FIG. 6D is a perspective view. [Figure 7] 10A and 10B are explanatory views for comparison showing the difference between a conventional example and an embodiment of the present invention with respect to the manner in which a pipe body moves when a pipe joint is crimped. [Figure 8] FIG. 1 is a front view showing a conventional pipe joint. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Fig. 1 is an explanatory diagram showing the overall configuration of a pipe fitting according to an embodiment of the present invention, showing a state before a pipe body is inserted and crimped, where Fig. 1(a) is a front view, Fig. 1(b) is a cross-sectional view taken along line AA in Fig. 1(a), and Fig. 1(c) is a perspective view. Fig. 2 is an explanatory diagram showing the overall configuration of a pipe fitting according to an embodiment of the present invention, showing a state after a pipe body is inserted and crimped, where Fig. 2(a) is a front view, Fig. 2(b) is a cross-sectional view taken along line AA in Fig. 2(a), and Fig. 2(c) is a perspective view.

[0010] As shown in Figures 1 and 2, the pipe fitting 100 of an embodiment of the present invention is configured such that the connection side end of a pipe H, which is covered with a pipe 2, is inserted along the outer peripheral surface of a nipple 1 and tightened, thereby radially clamping the connection side end of the pipe H between the outer peripheral surface of the nipple 1 and the inner peripheral surface of the pipe 2, thereby connecting the inner peripheral surface of the pipe H in intimate contact with the outer peripheral surface of the nipple 1.

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

[0012] As shown in Fig. 3, the outer peripheral surface of the nipple 1 is provided with a plurality of projections 11 in succession in the axial direction or with a plurality of projections at appropriate intervals. The line connecting the maximum heights has a substantially uniform diameter from the nipple tip 12 on the front side in the tube insertion direction to the rear side in the tube insertion direction. The recesses 11 may have a smooth shape on the rear side in the tube insertion direction from the plurality of projections 11 having a substantially uniform diameter, and may have a shape slightly smaller in diameter than the outer diameter of the projections 11, which makes it easier to set the hose. In addition, in the figure, the projections 11 are in a form in which symmetrical shapes are repeated in sequence, but the projections may have a bamboo shoot-like shape in which a sharp apex is formed by a locking surface that stands at an angle substantially perpendicular or close to the axis and an inclined surface that gradually becomes smaller in diameter toward the tip side.

[0013] In the conventional example, there is no taper provided to make it easier to insert a hose, that is, a tapered shape in which the tip side of the nipple outer periphery is narrow and becomes wider toward the back side. Also, a connection part 13 for connecting to another device is integrally provided on the axial base end side of the nipple 1, but the shape of the connection part 13 is not limited to that shown in the figure.

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

[0015] As shown in Figures 4(b) and 4(d), the inner circumferential surface of the pipe 2 has a minimum diameter at a position on the rear side of the position facing the nipple tip 12 at a portion on the front side in the pipe insertion direction (please also refer to Figures 5(b) and 5(d)). From the rear position where the minimum diameter is reached to the rear side in the pipe insertion direction, the diameter is the same over a predetermined range 21, that is, the minimum diameter.

[0016] Further back beyond the predetermined range 21, a first tapered section 22 is provided, the diameter of which increases toward the back side. The first tapered section 22 has a plurality of projections and recesses continuously provided in the axial direction, or a plurality of projections and recesses provided at appropriate intervals. A second tapered section 23 is provided from the back side position where the diameter is minimum to the front side, the diameter of which increases toward the front side. However, it is also possible to form a step shape in which the diameter increases all at once from the back side position where the diameter is minimum. In order to prevent the tube from breaking, it is more important that a part of the inner peripheral surface of the pipe 2 on the front side in the tube insertion direction is made to have the minimum diameter at a position further back than the position facing the nipple tip 12.

[0017] The pipe 2 is made of a rigid material such as stainless steel or aluminum that undergoes compressive deformation when pressure is applied in the radial direction by the crimping machine but does not recover due to 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 crimped, when the outer periphery of the pipe 2 is pressed from the outside toward the center, the position of the tip where the minimum diameter is mentioned above is stretched and becomes aligned with the position of the nipple tip. In addition, the multiple continuous unevennesses on the first tapered portion 22 on the inner surface of the pipe 2 and the multiple continuous unevennesses 11 on the outer surface of the nipple 1 are arranged so that the positions of each unevenness alternately intermesh, thereby clamping the pipe H and maintaining a high pulling-out force.

[0018] Pipe H is made of thermoplastic resin or thermosetting resin. Thermoplastic resins include general-purpose plastics such as polyvinyl chloride, polyolefin, polyurethane, and polyamide, engineering plastics with a heat resistance of 100°C or more, and super engineering plastics with a heat resistance of approximately 150°C or more. Thermosetting resins include silicone rubber and other rubbers, and the like, are appropriately selected depending on the application. Also, as in the technology described in Patent Document 2, it is possible to configure a laminated pipe by bonding dissimilar materials, an inner layer of fluororesin and an outer layer of silicone rubber, via reinforcing threads made of synthetic resin fibers such as polyester. In this case, silicone rubber is a material that is weak against tearing, and fluororesin is flexible, so it must be made thin, making it less tearable, but by combining it with this pipe fitting, it is possible to prevent the pipe H from breaking.

[0019] Next, a method for connecting a pipe H using the pipe joint 100 will be described according to the assembly procedure. First, the pipe 2 shown in Fig. 4 is placed over the outer periphery of the pipe H. Next, the nipple 1 shown in Fig. 3 is inserted into the pipe H with the pipe 2 covering it. Of course, depending on the operator's preference, the nipple 1 shown in Fig. 3 may be inserted into the pipe H first, and then the pipe 2 shown in Fig. 4 may be placed over the pipe H with the nipple 1 inserted. Because there is a certain amount of clearance between the pipe 1 before it is crimped, the operator may carry out the work in an order that is easy for him or her to handle.

[0020] After the nipple 1, tube H, and pipe 2 are arranged in this order from the inside to the outside, the pipe 2 is pressed by a crimping machine. In Fig. 6, the crimping machine S is called an eight-way crimping machine, and is configured to crimp eight points on the outer circumferential surface of the pipe 2 with the same pressure using eight jaws S1 called dies. By pinching the connection side end of the pipe H radially between the outer circumferential surface of the nipple 1 and the inner circumferential surface of the pipe 2, the inner circumferential surface of the pipe H is brought into close contact with the outer circumferential surface of the nipple 1, completing the connection.

[0021] The reason why the pipe fitting 100 according to the embodiment of the present invention is less likely to break than conventional pipe fittings will be explained using Figure 7. Figure 7(a) shows a conventional example, and Figure 7(b) shows the pipe fitting 100 according to the embodiment of the present invention, both of which are enlarged views of the upper part where the nipple, hose, and pipe overlap.

[0022] As shown in Fig. 7(a), nipples in conventional pipe joints are tapered to make it easier to insert a hose. However, because of this taper, when the pipe P is crimped with a crimping machine, if the pipe H is tightened from the point where the gap between the nipple N and the pipe P is narrow, the pipe H moves as if it is pushed out to the right along the thick arrow shown in the figure. When the pipe H behaves in this way, the pipe H becomes thicker as it moves and is pressed firmly against the nipple tip N1 and the pipe tip P1, causing stress concentration that can cause the pipe H as a hose to break.

[0023] On the other hand, in the pipe fitting 100 according to the embodiment of the present invention, the nipple 1 is not tapered, but the pipe 2 is tapered. As shown in FIG. 7(b), the pipe 2 has a minimum diameter at a position on the rear side of the position facing the nipple tip 12, and has the same diameter over a predetermined range 21 from the rear position where the diameter is minimum to the rear side in the pipe insertion direction, and is configured to have a first tapered portion that gradually expands in diameter further beyond the predetermined range 21. The pipe 2 is also configured to have a second tapered portion that gradually expands in diameter from the rear position where the diameter is minimum to the front side. As a result, the pipe H is pushed out and moves to both the left and right sides from the predetermined range 21 as shown in the figure. Therefore, the wall thickness of the pipe H that is pressed against the nipple tip 12 is smaller than that of the conventional example. Furthermore, the pipe H that moves due to the second tapered portion escapes to the upper side in the figure, so that stress concentration does not occur at the nipple tip 12. Furthermore, the stress concentration occurring at the tip of the pipe 2 is small enough to not cause any problem. EXAMPLES

[0024] The following describes an embodiment of the present invention. [Examples 1 and 2 and Comparative Examples 1 and 2] Examples 1 and 2 and Comparative Examples 1 and 2 shown in Table 1 have a three-layer structure of an inner layer, which is the innermost layer, a reinforcing layer made of braided reinforcing yarn, and an outer layer, made of the materials shown in the examples and comparative examples. Evaluation samples of the same size were then prepared for each of the examples. The pipe H used in Example 1 and Comparative Example 1 has an inner layer made of silicone rubber, a reinforcing layer made of polyester reinforcing thread, and an outer layer made of silicone rubber. The pipe H used in Example 2 and Comparative Example 2 has an inner layer made of fluororesin ETFE, a reinforcing layer made of polyester reinforcing thread, and an outer layer made of silicone rubber. The pipe fittings used in Comparative Example 1 and Comparative Example 2 are conventional pipe fittings tapered toward the nipple tip, and the pipe fittings used in Example 1 and Example 2 are pipe fittings according to an embodiment of the present invention.

[0025] [Evaluation Criteria] The evaluation results shown in Table 1, including the water pressure resistance test, bending test, liquid pooling test, and overall evaluation, are based on the following indicators. The "water pressure resistance test" is a test in which Example 1 and Example 2 and Comparative Example 1 and Comparative Example 2 are connected to a water pressure resistance tester, and a water pressure of a multiple of normal pressure (water temperature 23°C: 0.5 MPa) is applied to each evaluation sample for a certain period of time (3 minutes), and the water pressure at which each evaluation sample bursts is measured. The test results were evaluated on a three-point scale. The results of the water pressure resistance test were evaluated as follows: ◎: No burst or leakage even at more than three times the normal pressure, ○: Burst or leakage at twice the normal pressure, ×: Burst or leakage at (1 time) the normal pressure. The "bending test" is a test in which a continuous bending test with metal fittings is performed using Examples 1 and 2 and Comparative Examples 1 and 2 to confirm whether or not breaks occur in either the inner layer portion or the outer layer portion. The test results are evaluated on a three-point scale. The evaluation results of this "bending test" were evaluated as follows: ○: no breakage, △: signs of breakage, ×: breakage. Here, the continuous bending test with metal fittings is a test for comparing the bending performance and pressure resistance performance of each evaluation sample. To explain in detail, a metal fitting (pressure-resistant nipple) was inserted and attached to one end opening of each evaluation sample to close it, and the other end opening of each evaluation sample was closed and a load (2 kg) was attached to support it in a substantially vertical state. Air of a predetermined pressure was intermittently supplied to the inside of each evaluation sample to create an air hammer state, and the metal fitting (pressure-resistant nipple) side was bent from the vertical state to the left and right at about 90 degrees at regular intervals and repeatedly swung (20,000 times), and the change in state of each evaluation sample was observed. Here, the test results were evaluated in three stages using Example 1 and Example 2 and Comparative Example 1 and Comparative Example 2. In the "liquid pooling test," the pipe joints of the evaluation samples of Examples 1 and 2 and Comparative Examples 1 and 2 were blocked, colored ink was poured into the other end opening of each evaluation sample, and the other end opening was blocked while air at normal pressure was intermittently supplied to pressurize for 24 hours, after which the ink was removed and the sample was dried, and then cut and disassembled to observe changes in the state of ink penetration into the pinched parts of the pipe joints, etc. The test results were evaluated on a three-point scale. The results of the liquid pooling test were evaluated on a three-level scale, with ◯: no ink penetration, Δ: signs of ink penetration, and ×: ink penetration occurring. The "overall evaluation" was a three-level comprehensive evaluation based on the results of the aforementioned "water pressure resistance test," "bending test," and "liquid pooling test." The overall evaluation results were rated as follows: ⊚: best, ◯: good, ×: not suitable.

[0026] [Table 1]

[0027] In this way, by adopting a shape such as that of the pipe fitting 100 according to the embodiment of the present invention, the expansion of the pipe H can be suppressed within the pipe 2, and the amount of hose discharge from the tip of the pipe 2 can be reduced. Therefore, stress concentration does not occur, and even if the amount of crimping is increased, breakage of the pipe H can be effectively prevented. Furthermore, since the amount of crimping can be increased, it is also possible to prevent liquid from entering the inside of the pipe H at the nipple tip N1 and forming a pool.

[0028] The pipe body having a 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 described. However, the specific configuration is not limited to these embodiments, and the present invention includes design changes within the scope of the present invention. For example, in order to prevent the pipe from breaking, it is important that a part of the inner circumferential surface of the pipe 2 on the front side in the pipe body insertion direction is made to have a minimum diameter at a position on the rear side of the position facing the nipple tip 12. In other words, even if a step is formed instead of the second tapered portion, the pipe joint can be expected to perform the intended function. However, a taper is advantageous in that the hose can be moved smoothly. [Explanation of symbols]

[0029] 1 nipple 11 Unevenness 12 Nipple tip 13 Connection 2. Pipe 21 Prescribed range 22 First taper section 23 Second taper section 100 Pipe fittings H tube S crimping machine S1 Dice

Claims

1. In a pipe fitting, a pipe is inserted along the outer periphery of a nipple, and then a pipe is pressed from the outside to bring the inner periphery of the pipe into close contact with the outer periphery of the nipple. The nipple has an outer peripheral surface with projections and recesses, and a line connecting the maximum heights of the nipple has a substantially uniform diameter from the nipple tip on the front side in the tube insertion direction to the rear side in the tube insertion direction, 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.

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