Manufacturing method for pipe with resin joint

Abstract

To manufacture a pipe with a resin joint that has a high sealing performance between a metal pipe and the resin joint.SOLUTION: A manufacturing method for a pipe with a resin joint includes: a pretreatment step of roughening an outer surface of an end 11E of a metal pipe 11; a first mounting step of mounting the resin joint 12 to the roughened end 11E; a heating step of heating a fitting part between the metal pipe 11 and the resin joint 12 in a state where the resin joint 12 is fitted to the metal pipe 11; a pressing step of pressing the resin joint 12 toward the end 11E of the metal pipe 11; a cooling step of cooling the resin joint 12; and a second mounting step of mounting a reinforcing member 13 on the outer surface of the resin joint 12 after cooling the resin joint 12. A linear expansion coefficient of the reinforcing member 13 is smaller than the linear expansion coefficient of the resin joint 12.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a method for producing a pipe with a resin joint. [Background technology]

[0002] Conventionally, methods for joining different materials with high joining strength or high sealing property have been proposed. For example, Patent Document 1 describes a method for joining a metal molded body and a resin molded body. In the method described in Patent Document 1, the metal molded body is roughened, and the resin molded body is pressed against the roughened first roughened portion, and the surface of the resin molded body corresponding to the first roughened portion is fused. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-30445 Summary of the Invention [Problem to be solved by the invention]

[0004] Joining of dissimilar materials is also used when connecting pipes made of dissimilar materials. For example, when connecting a metal pipe and a plastic pipe, a plastic joint may be used. In this case, the plastic joint is joined to the metal pipe, which is a dissimilar material.

[0005] The above-mentioned configuration may be adopted, for example, in a vehicle pipe used inside a vehicle. In this case, the temperature inside the vehicle is high, and a fluid such as a refrigerant for a vehicle air conditioner flows through the pipe at high pressure for a long period of time. Even under such severe conditions, it is desirable to maintain a high sealability at the joint between different materials, such as a resin joint and a metal pipe.

[0006] The inventors of the present application manufactured a pipe with a plastic joint by roughening a metal pipe and attaching a plastic joint to the roughened portion as in the method described in the cited document 1. Then, using the pipe with a plastic joint, an experiment was carried out simulating a severe condition inside a vehicle. As a result, it was found that the fluid flowing through the pipe leaked from between the plastic joint and the metal pipe.

[0007] An object of the present invention is to provide a method for manufacturing a pipe with a resin joint having high sealing properties. [Means for solving the problem]

[0008] The manufacturing method of a pipe with a plastic joint disclosed in this specification is a manufacturing method of a pipe with a plastic joint in which a plastic joint is joined to a metal pipe, and includes a pretreatment step of roughening the outer surface of the end of the metal pipe, a first attachment step of attaching a tubular resin joint to the roughened end, a heating step of heating an attachment portion of the metal pipe and the resin joint while the resin joint is attached to the metal pipe, a pressing step of pressing the resin joint toward the end of the metal pipe while the attachment portion of the metal pipe and the resin joint is heated, a cooling step of cooling the resin joint after pressing the resin joint against the metal pipe, and a second attachment step of attaching a reinforcing member to the outer surface of the resin joint after cooling the resin joint, wherein the linear expansion coefficient of the reinforcing member is smaller than the linear expansion coefficient of the resin joint.

[0009] In this specification, a "pipe" is a cylindrical member. In this specification, a "pipe" includes not only what is called a "pipe," but also what is called a "hose" and what is called a "tube."

[0010] According to the above method, the resin joint is heated, pressed, and cooled to adhere the resin joint to the end of the metal pipe treated in the pretreatment process, and then the reinforcing member is attached to the resin joint. The reinforcing member is not attached in the process up to adhering the resin joint to the end of the metal pipe. As a result, even if the resin joint expands when the metal pipe with the resin joint is used at high temperatures and the resin joint then shrinks, almost no gap is generated between the resin joint and the reinforcing member. Furthermore, since the linear expansion coefficient of the reinforcing member is smaller than the linear expansion coefficient of the resin joint, the outward expansion of the resin joint at high temperatures is suppressed by the reinforcing member. Therefore, almost no gap is generated between the resin joint and the reinforcing member. As a result, even if the resin joint softens at high temperatures, the resin joint can be prevented from peeling off from the metal pipe. As a result, the fluid flowing through the metal pipe is less likely to leak between the metal pipe and the resin joint. As a result of the above, a pipe with a resin joint can be obtained which has high sealing performance between the metal pipe and the resin joint.

[0011] In the heating step, the metal pipe may be heated by a heating device, thereby heating a fitting portion between the metal pipe and the resin joint.

[0012] The above method makes it possible to heat the attachment portion between the metal pipe and the plastic joint, while suppressing heating of portions of the plastic joint other than the portion facing the metal pipe, such as the outer surface of the plastic joint and the portion where another pipe is connected.

[0013] The reinforcing member may be a tubular member.

[0014] When the reinforcing member is a tubular member, the outer surface of the plastic joint is covered with the reinforcing member, which makes it more difficult for the plastic joint to peel off from the metal pipe, thereby improving the sealing performance between the plastic joint and the metal pipe.

[0015] In the second mounting step, the reinforcing member may be pressed toward the resin joint in a radial direction of the resin joint to bring an inner surface of the reinforcing member into close contact with an outer surface of the resin joint.

[0016] By using such a simple method, it is possible to make the plastic joint less likely to peel off from the metal pipe.

[0017] From another perspective, in the second installation step, the reinforcing member having an inner diameter equal to or smaller than the outer diameter of the plastic joint may be pushed into the plastic joint from the axial direction of the plastic joint so that the reinforcing member is positioned on the outside of the plastic joint, thereby bringing the inner surface of the reinforcing member into close contact with the outer surface of the plastic joint.

[0018] By using such a simple method, it is possible to make the plastic joint less likely to peel off from the metal pipe.

[0019] From another perspective, the outer surface of the resin joint has a tapered portion whose outer diameter increases as it approaches one end in the axial direction, the reinforcing member is a tubular member, the inner surface of the reinforcing member has a tapered portion whose inner diameter increases as it approaches one end in the axial direction, and in the second installation step, the reinforcing member is pushed toward the resin joint so that the direction in which the outer diameter of the resin joint increases and the direction in which the inner diameter of the reinforcing member increases are the same in the axial direction of the resin joint and the reinforcing member is positioned outside the resin joint, and the inner surface of the reinforcing member and the outer surface of the resin joint are closely attached to each other.

[0020] By using such a simple method, it is possible to make the plastic joint less likely to peel off from the metal pipe. Effect of the Invention

[0021] According to the above method, it is possible to provide a method for manufacturing a pipe with a resin joint having high sealing properties. [Brief description of the drawings]

[0022] [Figure 1] FIG. 2 is a front view of an example of a pipe with a resin joint and another pipe. [Diagram 2] FIG. 2 is a cross-sectional view of an example of a pipe with a resin joint and another pipe. [Diagram 3] FIG. 4 is a diagram showing a pretreatment step in the manufacturing method of a resin joint-equipped pipe according to the first embodiment. [Figure 4] FIG. 4 is a view showing a state after a pretreatment step in the manufacturing method of a resin joint-equipped pipe according to the first embodiment. [Diagram 5] FIG. 2 is a diagram showing a first attachment step in the method for manufacturing a resin joint-equipped pipe according to the first embodiment. [Figure 6] FIG. 3 is a diagram showing a heating step in the method for producing a resin joint-equipped pipe according to the first embodiment. [Figure 7] 4A to 4C are diagrams showing a pressing step in the method for manufacturing a resin joint-equipped pipe according to the first embodiment. [Figure 8] FIG. 4 is a diagram showing a cooling step in the method for manufacturing a resin jointed pipe according to the first embodiment. [Figure 9] 4A to 4C are views showing a state after a cooling step in the manufacturing method for a resin joint-equipped pipe according to the first embodiment. [Figure 10] 5A to 5C are diagrams showing a second mounting step in the manufacturing method for a resin joint-equipped pipe according to the first embodiment. [Figure 11] 13 is a view showing a state after a cooling step in the manufacturing method for a resin joint-equipped pipe according to the second embodiment. FIG. [Figure 12] 13 is a diagram showing a second mounting step in the manufacturing method for a resin joint-equipped pipe according to the second embodiment. FIG. [Figure 13] 13A and 13B are views showing a state after a pretreatment step in the manufacturing method of a resin joint-equipped pipe according to the third embodiment. [Figure 14] 13A to 13C are diagrams showing a heating step in a manufacturing method for a resin joint-equipped pipe according to a third embodiment. [Figure 15] 13A to 13C are diagrams showing a pressing step in a manufacturing method for a resin joint-equipped pipe according to a third embodiment. [Figure 16]13 is a view showing a state after a cooling step in the manufacturing method for a resin joint-equipped pipe according to the third embodiment. FIG. [Figure 17] 13 is a diagram showing a second mounting step in the manufacturing method for a resin joint-equipped pipe according to the third embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] [First embodiment] 1 shows a state in which a resin joint-equipped pipe 1 is connected to another pipe 2. The resin joint-equipped pipe 1 and the pipe 2 are used, for example, as a vehicle pipe. Examples of vehicle pipes include air conditioning pipes and fuel pipes.

[0024] As shown in Figures 1 and 2, the pipe with a resin joint 1 has a metal pipe 11, a resin joint 12, and a reinforcing member 13. As shown in Figure 2, the metal pipe 11 and a pipe 2 are in communication. The resin joint 12 connects the metal pipe 11 and the pipe 2. The pipe 2 is, for example, a resin pipe.

[0025] The metal pipe 11 is tubular. The metal pipe 11 may be, for example, cylindrical or rectangular. Although the metal pipe 11 shown in Fig. 1 is curved, the shape of the metal pipe 11 can be changed.

[0026] "Cylindrical" means that there is a hole penetrating in the axial direction. The hole penetrating in the axial direction may have the same shape from one end to the other end in the axial direction, or may have a different shape in one part of the axial direction from the other part. A "cylindrical" member may be a member whose outer shape and inner shape are the same from one end to the other end in the axial direction, or may be a member whose outer shape and / or inner shape are different in one part of the axial direction from the other part. For example, "cylindrical" may mean that the outer diameter is the same from one end to the other end in the axial direction, the inner diameter is the same from one end to the other end in the axial direction, the outer diameter of one part of the axial direction may be different from the outer diameter of the other part, and the inner diameter of one part of the axial direction may be different from the inner diameter of the other part.

[0027] The material of the metal pipe 11 is a metal, for example, iron, copper, a copper alloy, aluminum, an aluminum alloy, magnesium, a magnesium alloy, or stainless steel, but is not limited thereto.

[0028] The resin joint 12 is tubular as shown in Fig. 2. The definition of "tubular" is the same as that of "tubular" explained for the metal pipe 11. The resin joint 12 may be, for example, cylindrical or rectangular. When the metal pipe 11 is cylindrical, the resin joint 12 is cylindrical. When the metal pipe 11 is rectangular, the resin joint 12 is rectangular.

[0029] The resin joint 12 may be made of a material such as a thermoplastic resin or an elastomer. Examples of the thermoplastic resin include polyamide (PA), polyethylene (PE), polypropylene (PP), polystyrene (PS), acrylonitrile / styrene resin (AS), acrylonitrile / butadiene / styrene resin (ABS), methacrylic resin (PMMA), and polyvinyl chloride (PVC). Examples of the elastomer include a thermoplastic elastomer. The resin joint 12 may contain additives such as a filler and a flame retardant.

[0030] The reinforcing member 13 shown in Fig. 1 and Fig. 2 is tubular as shown in Fig. 2. The definition of "tubular" is the same as that of "tubular" explained for the metal pipe 11. The reinforcing member 13 may be, for example, cylindrical or rectangular. When the resin joint 12 is cylindrical, the reinforcing member 13 is cylindrical. When the resin joint 12 is rectangular, the reinforcing member 13 is rectangular.

[0031] The linear expansion coefficient of the reinforcing member 13 is smaller than that of the resin joint 12. The linear expansion coefficient is sometimes referred to as the thermal expansion coefficient. As long as the linear expansion coefficient of the reinforcing member 13 is smaller than that of the resin joint 12, the material of the reinforcing member 13 is not particularly limited. The material of the reinforcing member 13 may be, for example, a metal, a thermoplastic resin, a thermosetting resin, or an elastomer. For example, when the material of the reinforcing member 13 is a metal, the linear expansion coefficient of the reinforcing member 13 is smaller than that of the resin joint 12. Examples of the metal include the metals exemplified as the material of the metal pipe 11. As long as the linear expansion coefficient of the reinforcing member 13 is smaller than that of the resin joint 12, the material of the reinforcing member 13 may be a thermoplastic resin, a thermosetting resin, an elastomer, or the like.

[0032] Next, a method for manufacturing the pipe with a resin fitting 1 will be described. In Fig. 1, the pipe 2 is connected to the resin fitting 12, but the connection of the pipe 2 to the resin fitting 12 may be performed before manufacturing the pipe with a resin fitting 1, during manufacturing the pipe with a resin fitting 1, or after manufacturing the pipe with a resin fitting 1. In the following, a case will be described in which after the resin joint-equipped pipe 1 is manufactured, the pipe 2 is connected to the resin joint 12.

[0033] [Pretreatment process] As shown in Fig. 3, a metal pipe 11 is prepared. The outer surface of the end 11E of the metal pipe 11 is roughened. The roughening treatment may be a known roughening treatment. For example, the roughening treatment may be performed by laser processing, polishing, blasting, cutting, rolling, knurling, or the like.

[0034] FIG. 4 shows the metal pipe 11 after the surface roughening treatment. The outer surface of the end 11E of the metal pipe 11 is uneven. The roughness of the end 11E of the metal pipe 11 after the surface roughening treatment is not particularly limited. For example, the surface roughness Rz may be about 100 μm. Rz is the maximum height roughness. The maximum height roughness (Rz) is the sum of the height of the highest peak (Rp) and the depth of the lowest valley (Rv) in the surface-roughened end 11E.

[0035] [First installation process] A resin joint 12 is attached to the end 11E of a metal pipe 11. Fig. 5 shows the state in which the resin joint 12 is attached to the end 11E of the metal pipe 11. The end 11E of the metal pipe 11 is present inside the resin joint 12. When the resin joint 12 is attached to the end 11E of the metal pipe 11, a gap exists between the outer surface of the end 11E and the inner surface of the resin joint 12.

[0036] [Heating process] With the resin joint 12 attached to the end 11E of the metal pipe 11, the attachment portion between the metal pipe 11 and the resin joint 12 is heated. The "attachment portion between the metal pipe 11 and the resin joint 12" refers to the "portion of the metal pipe 11 facing the resin joint 12" and the "portion of the resin joint 12 facing the metal pipe 11". The "portion of the metal pipe 11 facing the resin joint 12" refers to the "outer surface of the end 11E of the metal pipe 11 and its vicinity". The "portion of the resin joint 12 facing the metal pipe 11" refers to the "inner surface of the resin joint 12 facing the end 11E of the metal pipe 11 and its vicinity".

[0037] The method of heating the fitting portion between the metal pipe 11 and the resin joint 12 is not particularly limited. For example, as shown in Fig. 6, a portion of the metal pipe 11 away from the end 11E is heated by a heating device. Heat is transferred from the heated portion to the end 11E of the metal pipe 11, thereby heating the end 11E of the metal pipe 11. Heat is transferred from the end 11E of the metal pipe 11 to the inner surface of the resin joint 12 facing the end 11E and its periphery. As a result, the fitting portion between the metal pipe 11 and the resin joint 12 is heated.

[0038] The heating method and heating device are not particularly limited. It is preferable to adopt a general heating method and heating device. The heating device may be, for example, a heater, a burner, or a high-frequency induction heating device.

[0039] "Heating the fitting portion between the metal pipe 11 and the resin joint 12" includes the case where the fitting portion between the metal pipe 11 and the resin joint 12 is not directly heated by a heating device, as described above.

[0040] By heating the attachment portion between the metal pipe 11 and the resin fitting 12, the inner surface of the resin fitting 12 facing the metal pipe 11 and its surroundings become heated to a temperature above the melting point or softening point of the resin fitting 12, thereby melting or softening.

[0041] When the fitting portion between the metal pipe 11 and the resin joint 12 is heated, the outer surface of the resin joint 12 and its periphery, and the portion of the resin joint 12 to which the other pipe 2 shown in FIG. 2 is connected are preferably not heated, or if heated, the temperature is lower than the softening point of the resin joint 12. This allows the outer surface of the resin joint 12 and the portion of the resin joint 12 to which the other pipe 2 shown in FIG. 2 is connected to be maintained in the same shape as before heating. For example, by the method shown in FIG. 6, the fitting portion between the metal pipe 11 and the resin joint 12 can be heated while suppressing heating of the outer surface of the resin joint 12 and its periphery, and the portion of the resin joint 12 to which the other pipe 2 shown in FIG. 2 is connected.

[0042] [Pressing process] In a state where the fitting part between the metal pipe 11 and the resin joint 12 is heated, the resin joint 12 is pressed toward the end 11E of the metal pipe 11. "In a state where the fitting part between the metal pipe 11 and the resin joint 12 is heated" means a state where the inner surface of the resin joint 12 facing the metal pipe 11 and its periphery are heated to a temperature higher than the melting point or softening point of the resin joint 12. During the heating process, the fitting part between the metal pipe 11 and the resin joint 12 is in a heated state, so that the resin joint 12 is pressed toward the end 11E of the metal pipe 11 during the heating process. As shown in FIG. 7, the part of the resin joint 12 facing the metal pipe 11 enters the recess of the end 11E of the metal pipe 11. As a result, there is almost no gap between the resin joint 12 and the end 11E of the metal pipe 11. The resin joint 12 is in close contact with the metal pipe 11.

[0043] [Cooling process] After the pressing step, the plastic joint 12 is cooled. For example, as shown in FIG. 8, a cooling gas may be flowed inside the metal pipe 11. According to this method, the metal pipe 11 is cooled first. Cooling heat is transferred from the cooled metal pipe 11 to the part of the plastic joint 12 facing the metal pipe 11, thereby cooling the part of the plastic joint 12 facing the metal pipe 11. As a result, the plastic joint 12 hardens while fitting into the irregularities of the end 11E of the metal pipe 11. There is almost no gap between the end 11E of the metal pipe 11.

[0044] The cooling method is not limited to the above. For example, the resin joint 12 may be cooled by blowing cold air from the outside of the resin joint 12. The resin joint 12 may also be cooled to the ambient temperature by leaving the metal pipe 11 and the resin joint 12 as they are.

[0045] [Second mounting process] After the cooling process, the reinforcing member 13 is attached to the resin joint 12. The method of attachment is not particularly limited. For example, a cylindrical reinforcing member 13 as shown in FIG. 9 is positioned on the outside of the resin joint 12. As shown in FIG. 10, the reinforcing member 13 is pressed toward the resin joint 12 from the outside. The resin joint 12 and the reinforcing member 13 are brought into close contact with almost no gap between them. The reinforcing member 13 does not come off the resin joint 12.

[0046] The above method provides a pipe 1 with a resin joint. By connecting the pipe 2 shown in Fig. 2 to the resin joint 12, a structure in which the metal pipe 11 and the pipe 2 are connected is obtained. When the pipe 2 is a resin pipe, the resin joint 12 and the pipe 2 are connected by, for example, laser welding or the like.

[0047] By manufacturing the resin jointed pipe 1 by the above method, the following effects can be obtained.

[0048] According to the above method, the resin joint 12 is cooled in a state where it is inserted into the recess of the end 11E of the roughened metal pipe 11, and the resin joint 12 is brought into close contact with the metal pipe 11, and then the reinforcing member 13 is attached to the resin joint 12. The reinforcing member 13 is not attached to the resin joint 12 in the process of bringing the resin joint 12 into close contact with the end 11E of the metal pipe 11. As a result, even if the resin joint 12 expands when the pipe 1 with a resin joint is used at high temperatures and then the resin joint 12 shrinks, almost no gap is generated between the resin joint 12 and the reinforcing member 13. Furthermore, since the linear expansion coefficient of the reinforcing member 13 is smaller than the linear expansion coefficient of the resin joint 12, the outward expansion of the resin joint 12 at high temperatures is suppressed by the reinforcing member 13. Therefore, almost no gap is generated between the resin joint 12 and the reinforcing member 13. As a result, almost no gap occurs between the resin joint 12 and the metal pipe 11. As a result, even if the resin joint 12 softens under high temperatures, it is possible to prevent the resin joint 12 from peeling off from the metal pipe 11. As a result, it is possible to prevent the fluid flowing through the metal pipe 11 from leaking from between the metal pipe 11 and the resin joint 12.

[0049] Furthermore, the experiments described below have shown that even under harsh conditions in which fluid is passed through the metal pipe 11 at high temperature and high pressure, the fluid flowing through the metal pipe 11 can be prevented from leaking between the metal pipe 11 and the resin joint 12.

[0050] As described above, according to the method of this embodiment, it is possible to manufacture a resin joint-equipped pipe 1 in which the sealing performance between the metal pipe 11 and the resin joint 12 is higher than in the past.

[0051] According to the above method, the attachment portion of the metal pipe 11 and the resin joint 12 is heated as shown in Fig. 6, and then the resin joint 12 is pressed against the metal pipe 11 as shown in Fig. 7. By pressing the resin joint 12 while it is being heated, the adhesion between the metal pipe 11 and the resin joint 12 is improved.

[0052] 10, the reinforcing member 13 and the resin joint 12 can be tightly attached with almost no gap between them by simply pressing the reinforcing member 13 against the resin joint 12. By using such a simple method, the resin joint 12 can be configured to be less likely to peel off from the metal pipe 11.

[0053] In addition, the fluid flowing through the metal pipe 11 is likely to flow into between the metal pipe 11 and the resin joint 12 from the tip of the end 11E of the metal pipe 11 shown in Fig. 10. Therefore, the resin joint 12 is most likely to peel off near the tip of the end 11E of the metal pipe 11. As shown in Fig. 10, the resin joint 12 and the reinforcing member 13 are present on the outside of the tip of the end 11E of the metal pipe 11 and its vicinity. Therefore, the resin joint 12 is less likely to peel off from the metal pipe 11 at the tip of the end 11E of the metal pipe 11 and its vicinity, where the resin joint 12 is likely to peel off.

[0054] In addition, since the reinforcing member 13 is cylindrical, the reinforcing member 13 is present on the outer surface of the resin joint 12. This can further improve the sealing performance between the metal pipe 11 and the resin joint 12. In addition, the reinforcing member 13 is present on the outer surface of the tip of the end 11E of the metal pipe 11 and its vicinity, where the resin joint 12 is likely to peel off. Therefore, the resin joint 12 is unlikely to peel off from the metal pipe 11 even in the portion where the resin joint 12 is likely to peel off.

[0055] Second Embodiment Next, a method for manufacturing a resin jointed pipe according to a second embodiment of the present invention will be described below with reference to Figures 11 and 12. The second embodiment differs from the first embodiment mainly in the second installation step. Note that the description of the same steps as those in the first embodiment will be omitted as appropriate. Also, the same reference numerals will be used for the same configurations as those in the first embodiment, and the description thereof will be omitted as appropriate.

[0056] The pretreatment step, the first mounting step, the heating step, and the cooling step are the same as the pretreatment step, the first mounting step, the heating step, and the cooling step of the first embodiment. Fig. 11 shows the metal pipe 11 and the resin joint 12, and the reinforcing member 213 after the cooling step.

[0057] The reinforcing member 213 is a cylindrical member. The tip of the reinforcing member 213 is convex toward the inside. The inner diameter of the portion of the reinforcing member 213 other than the tip is equal to or smaller than the outer diameter of the resin joint 12.

[0058] [Second mounting process] 12, the reinforcing member 213 is pushed into the resin joint 12 in the axial direction of the resin joint 12 so that the reinforcing member 213 is disposed on the outside of the resin joint 12. Then, the tip of the reinforcing member 213 is hooked onto one end of the resin joint 12 for positioning, whereby the reinforcing member 213 is attached to the resin joint 12. The resin joint 12 and the reinforcing member 213 are brought into close contact with almost no gap between them. The reinforcing member 213 does not come off the resin joint 12.

[0059] By the above method, in the second embodiment, a pipe with a resin joint having high sealing properties can be obtained, as in the first embodiment. Also, by the simple method of pushing a reinforcing member 213 having an inner diameter equal to or smaller than the outer diameter of the resin joint 12 into the resin joint 12 from the axial direction of the resin joint 12, it is possible to make the resin joint 12 less likely to peel off from the metal pipe 11.

[0060] Third Embodiment Next, a method for manufacturing a resin jointed pipe according to a third embodiment of the present invention will be described below with reference to Figs. 13 to 17. The third embodiment differs from the first embodiment mainly in the second mounting step. Note that the description of the same steps as those in the first embodiment will be omitted as appropriate. Also, the same reference numerals will be used to designate the same components as those in the first embodiment, and the description thereof will be omitted as appropriate.

[0061] The pretreatment step is the same as the pretreatment step in embodiment 1. Fig. 13 shows the metal pipe 11 and the resin joint 312 after the pretreatment step.

[0062] 13, the resin joint 312 has a tapered portion in which the outer diameter of the outer surface increases toward one end in the axial direction. The metal pipe 11 is disposed inside the tapered portion of the resin joint 312.

[0063] The first mounting step, heating step, pressing step, and cooling step described below are the same as the first mounting step, heating step, pressing step, and cooling step of the first embodiment. These steps will be briefly described below.

[0064] [First installation process] A resin joint 312 is attached to the end 11E of the metal pipe 11. Figure 14 shows the state in which the resin joint 312 is attached to the end 11E of the metal pipe 11. As shown in Figure 14, the tapered portion of the resin joint 312 has an outer surface area that increases in the axial direction of the metal pipe 11 as it moves away from one end of the end 11E of the metal pipe 11.

[0065] [Heating process] With the resin joint 312 attached to the end portion 11E of the metal pipe 11, the attachment portion between the metal pipe 11 and the resin joint 12 is heated as shown in FIG.

[0066] [Pressing process] During the heating process, the resin joint 312 is pressed towards the end 11E of the metal pipe 11. When pressing the resin joint 312, the resin joint 312 is pressed so as to maintain the tapered outer surface shape of the resin joint 312, as shown in FIG. 15 . By pressing the resin joint 312, there is almost no gap between the resin joint 312 and the end 11E of the metal pipe 11. The resin joint 12 is in close contact with the metal pipe 11.

[0067] [Cooling process] After the pressing step, the resin joint 312 is cooled.

[0068] 16 shows the metal pipe 11 and the resin joint 312 after the cooling process, and the reinforcing member 313. The reinforcing member 313 is a cylindrical member. The inner surface of the reinforcing member 313 is tapered such that the inner diameter increases toward one end in the axial direction.

[0069] [Second mounting process] 16, in the axial direction of the resin joint 312, the direction in which the outer diameter of the resin joint 312 increases and the direction in which the inner diameter of the reinforcing member 313 increases are the same. From this state, the reinforcing member 313 is pressed toward the resin joint 312 so that the reinforcing member 313 is disposed on the outside of the resin joint 312. The inner surface of the reinforcing member 313 is pressed against the outer surface of the resin joint 312, so that the resin joint 312 and the reinforcing member 313 are closely attached with almost no gap between them. The reinforcing member 313 does not come off the resin joint 312.

[0070] By the above method, in the third embodiment, a pipe with a resin joint having high sealing properties can be obtained, as in the first embodiment. In addition, by the simple method of pushing the reinforcing member 313 toward the resin joint 312, it is possible to make the resin joint 312 less likely to peel off from the metal pipe 11. EXAMPLES

[0071] The present invention will be described in more detail below with reference to examples. However, the following examples do not limit the present invention, and all modifications and variations within the scope of the present invention are included in the technical scope of the present invention.

[0072] (experiment) A resin jointed pipe was manufactured by the manufacturing method of the resin jointed pipe described in the first embodiment. Also, a resin jointed pipe was manufactured by partially changing the method described in the first embodiment. The test conditions and test results are shown in Table 1 and below.

[0073] An aluminum pipe was used as the metal pipe. A polyamide 66 pipe was used as the resin joint. A reinforcing member having the shape shown in Fig. 9 and Fig. 10 of the first embodiment was used as the reinforcing member. An aluminum reinforcing member was used as the reinforcing member.

[0074] As shown in Table 1, for No. 2, No. 4, and No. 6, a pretreatment process was performed on the metal pipes. In the pretreatment process, the outer surface of the end of the metal pipe was roughened by laser processing. The surface roughness Rz of the outer surface of the roughened end of the metal pipe was approximately 100 μm. For No. 1, No. 3, and No. 5, the metal pipes were not pretreated.

[0075] As shown in Table 1, in No. 1 and No. 2, a reinforcing member was not attached to the resin joint. In No. 3 to No. 6, a reinforcing member was attached to the resin joint, but the timing of attaching the reinforcing member was different. In No. 3 and No. 4, as described in the first embodiment, the reinforcing member was attached to the resin joint after the cooling process. In No. 5 and No. 6, during the heating process, the reinforcing member was positioned outside the resin joint, and the reinforcing member was pressed from the outside of the reinforcing member, thereby pressing the resin joint toward the metal pipe. In this way, in No. 5 and No. 6, the heating process, the pressing process, and the second mounting process were performed simultaneously. After that, the resin joint was cooled.

[0076] In the heating step, as shown in FIG. 6, a portion of the metal pipe away from the end was heated by a heating device, thereby heating the attachment portion between the metal pipe and the resin joint. In the cooling step, as shown in FIG. 8, a cooling gas was caused to flow inside the metal pipe to cool the plastic joint.

[0077] After producing the resin jointed pipes No. 1 to No. 6, test samples were made by connecting other pipes to each resin jointed pipe, and the following tests were carried out.

[0078] (Pressure Test) Gas was sealed in the test sample in a room temperature atmosphere, and the pressure inside the test sample was set to 3.53 MPa for 5 minutes. Water at a pressure of 5.30 MPa was then sealed in the test sample. In Table 1, cases where there was no water leakage were indicated as "○", and cases where there was water leakage were indicated as "×". In the following, "water leakage" may be simply referred to as "leakage".

[0079] (High temperature repeated pressure test) Assuming the harsh conditions inside a vehicle, the test oil was sealed in a test sample in an atmosphere of 140°C, and pressure was repeatedly applied from 0 MPa to 3.53 MPa inside the test sample. This pressure application was repeated 150,000 times. In Table 1, cases where there was no oil leakage are indicated as "○", and cases where there was an oil leakage are indicated as "×". In the following, "oil leakage" may be simply referred to as "leakage".

[0080] [Table 1]

[0081] From Table 1, the following was found:

[0082] In No. 1, No. 3, and No. 5, in which the metal pipe was not subjected to the pretreatment process, leakage occurred in the pressure test and the high-temperature repeated pressurization test. In No. 3 and No. 5, pipes with plastic joints were manufactured using the same manufacturing method as in the first embodiment except for the pretreatment process, but leakage occurred in the pressure test and the high-temperature repeated pressurization test. From the above, it was found that if the metal pipe is not subjected to the pretreatment process, the plastic joint will peel off from the metal pipe.

[0083] In No. 1 and No. 2, in which a reinforcing member was not attached to the plastic joint, leakage occurred during the high-temperature repeated pressure test. In No. 2, a plastic joint-attached pipe was manufactured using the same manufacturing method as in the first embodiment, except that a reinforcing member was not attached, but leakage occurred during the high-temperature repeated pressure test. This shows that if a reinforcing member is not attached to the plastic joint, the plastic joint will peel off from the metal pipe.

[0084] In No.3 to No.6, a reinforcing member was attached to the plastic joint. In No.3 and No.4, the reinforcing member was attached after the cooling process. In other words, in No.3 and No.4, the plastic joint was attached to the metal pipe after it was attached to the plastic joint. In No.3 and No.4, no leakage occurred in the pressure test and the high-temperature repeated pressure test. On the other hand, in No.5 and No.6, the second attachment process of attaching the reinforcing member was performed during the heating process of heating the plastic joint and the pressing process of pressing the plastic joint, and then the cooling process of cooling the plastic joint was performed. In other words, in No.5 and No.6, the reinforcing member was attached to the plastic joint during the process of attaching the plastic joint to the metal pipe. In No.5 and No.6, leakage occurred in the high-temperature repeated pressure test.

[0085] From Nos. 3 to 6, it was found that if a reinforcing member is attached to a plastic joint during the process of adhering the plastic joint to a metal pipe, the plastic joint will peel off from the metal pipe under severe conditions at high temperatures. However, if a reinforcing member is attached to the plastic joint after the plastic joint is adhered to the metal joint, the plastic joint will not peel off from the metal pipe even under severe conditions at high temperatures.

[0086] From the above, it has been found that by performing a pretreatment process on a metal pipe, and then attaching a reinforcing member to the resin joint after the resin joint is adhered to the metal pipe, it is possible to produce a pipe with a resin joint that has high sealing performance between the metal pipe and the resin joint, even under harsh conditions such as high temperatures.

[0087] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration should not be considered to be limited to these embodiments. The scope of the present invention is indicated by the claims, not by the above description, and includes all modifications within the meaning and scope of the claims.

[0088] For example, the reinforcing member (13, 213, 313) may or may not be cylindrical.

[0089] Moreover, the method of heating the attachment portion between the metal pipe (11) and the resin joint (12, 312) is not limited to the methods shown in FIGS.

[0090] Furthermore, the method of attaching the reinforcing member (13, 213, 313) to the resin joint (12, 312) is not limited to the methods described in the first, second and third embodiments.

[0091] In the second embodiment, as shown in Fig. 12, the tip of the reinforcing member 213 is hooked onto one end of the resin joint 12 to position it. However, the configuration for positioning the reinforcing member 213 to the resin joint 12 is not limited to the above and can be changed. For example, a recess may be formed between one end and the other end of the axial direction of the resin joint 12, and a protrusion facing inward may be present between one end and the other end of the reinforcing member 213, and the protrusion of the reinforcing member 213 may fit into the recess of the resin joint 12 to hook the reinforcing member to the resin joint to position it.

[0092] In the second embodiment, the reinforcing member 213 may be pressed toward the resin joint 12 after the reinforcing member 213 is pressed into the resin joint 12 and positioned.

[0093] In the third embodiment, the metal pipe 11, the resin joint 312, and the reinforcing member 313 are cylindrical, but they may be rectangular tubular.

[0094] From a different viewpoint from the above-mentioned embodiment and modified examples, instead of roughening the outer surface of the end of the metal pipe in the above-mentioned embodiment and modified examples, a pipe with a resin joint can also be manufactured by applying an adhesive to the outer surface of the end of the metal pipe. For example, in the second embodiment, as shown in FIG. 11, the end 11E of the metal pipe 11 is roughened. However, in the pretreatment step of the second embodiment, instead of roughening the end 11E of the metal pipe 11, an adhesive is applied to the end 11E of the metal pipe 11, thereby manufacturing a pipe with a resin joint. Similarly, in the third embodiment, instead of roughening the end 11E of the metal pipe 11 in the pretreatment step of the third embodiment, an adhesive is applied to the end 11E of the metal pipe 11, thereby manufacturing a pipe with a resin joint. [Explanation of symbols]

[0095] 1 Pipe with plastic fitting 2. Pipe 11 Metal Pipe 12, 312 Plastic joints 13, 213, 313 Reinforcement members

Claims

1. A method for manufacturing a resin joint-equipped pipe in which a resin joint is joined to a metal pipe, comprising the steps of: A pretreatment step of roughening the outer surface of the end of the metal pipe; A first mounting step of mounting a cylindrical resin joint to the roughened end; a heating step of heating an attachment portion between the metal pipe and the resin joint in a state where the resin joint is attached to the metal pipe; a pressing step of pressing the resin joint toward the end of the metal pipe while heating an attachment portion between the metal pipe and the resin joint; a cooling step of pressing the resin joint against the metal pipe and then cooling the resin joint; A second mounting step of mounting a reinforcing member on an outer surface of the resin joint after cooling the resin joint; Equipped with The linear expansion coefficient of the reinforcing member is smaller than the linear expansion coefficient of the resin joint. A method for manufacturing a pipe with a resin joint, comprising:

2. In the heating step, 2. The method for manufacturing a pipe with a resin joint according to claim 1, wherein the metal pipe is heated by a heating device, thereby heating a mounting portion between the metal pipe and the resin joint.

3. 3. The method for manufacturing a resin joint-equipped pipe according to claim 1, wherein the reinforcing member is a tubular member.

4. In the second mounting step, 3. A method for manufacturing a pipe with a plastic joint as described in claim 1 or 2, characterized in that the reinforcing member is pressed toward the plastic joint in a radial direction of the plastic joint to tightly contact an inner surface of the reinforcing member with an outer surface of the plastic joint.

5. In the second mounting step, 3. A method for manufacturing a pipe with a plastic joint as described in claim 1 or 2, characterized in that the reinforcing member having an inner diameter equal to or smaller than the outer diameter of the plastic joint is pushed into the plastic joint from the axial direction of the plastic joint so that the reinforcing member is positioned on the outside of the plastic joint, thereby closely adhering the inner surface of the reinforcing member to the outer surface of the plastic joint.

6. The outer surface of the resin joint has a tapered portion in which the outer diameter increases toward one end in the axial direction, The reinforcing member is a cylindrical member, The inner surface of the reinforcing member has a tapered portion whose inner diameter increases toward one end in the axial direction, In the second mounting step, 3. A method for manufacturing a pipe with a resin joint as described in claim 1 or 2, characterized in that in the axial direction of the resin joint, the direction in which the outer diameter of the resin joint increases and the direction in which the inner diameter of the reinforcing member increases are the same, and the reinforcing member is pushed toward the resin joint so that the reinforcing member is positioned outside the resin joint, thereby tightly adhering the inner surface of the reinforcing member to the outer surface of the resin joint.

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