How to seal pipe ends

Abstract

To provide a sealing method of a pipe end part which can prevent dirt of a metal mold and the like, which can correspond to various pipe diameters and the shape or size of a flat part formed at the pipe end part, and which has excellent adhesiveness between a sealer and a pipe inner surface.SOLUTION: A sealing method of a pipe end part in which a pipe end part 2 is pressed and a pipe 1 is formed into a tabular flat part 10, a gradual swelling part 13 in which a cross section gradually swells from the flat part 10, and a circular part 15 in which the cross section is kept circular includes: a coating step of coating a pipe inner surface 3 of the pipe end part 2 with a sealer 21 annularly by using a nozzle 20; a curing step of curing the sealer 21 and making it adhere to the pipe inner surface 3; and a press step of crushing the pipe end part 2 to form the flat part 10, and compressing the annularly applied sealer 21 for sealing.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a technique for sealing a pipe end by crushing it flat. [Background technology]

[0002] Conventionally, when sealing a pipe end by crushing it flat, a technique has been adopted in which a paste-like sealant is applied to the inside of the pipe to seal it. In addition, Japanese Patent Publication No. 59-14287 (Patent Document 1) discloses a technique in which a seal member is inserted in advance into a molded part of one end of the pipe, and then a jig is inserted from the opposite side to press the molded part. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 59-14287 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the technology of applying a paste-like sealer to the inside of the pipe to seal it, the uncured sealer adheres to the mold, and cleaning the equipment such as the mold takes a lot of time. On the other hand, in the technology disclosed in Patent Document 1, it is necessary to change the shape and size of the sealing member each time depending on the diameter of the pipe and the shape or size of the flat part pressed into a flat shape at the end. In addition, since the sealing member is simply placed inside the pipe, there is also a problem that the adhesion between the sealing member and the inner surface of the pipe is poor.

[0005] The present invention has been made in consideration of the above points, and aims to provide a method for sealing a pipe end that can prevent contamination of a mold, etc., can accommodate various pipe diameters and shapes or sizes of flattened portions formed on the pipe end, and has excellent adhesion between the sealer and the inner surface of the pipe. [Means for solving the problem]

[0006] The method for sealing a pipe end of the present invention comprises the steps of: A method for sealing a pipe end, comprising pressing the pipe end to form a plate-like flat section, a gradually expanding section whose cross section gradually expands from the flat section, and a circular section whose cross section is maintained circular, comprising: a coating step of applying a sealer in an annular shape to an inner surface of the pipe at the end of the pipe using a nozzle; a curing step for curing the sealer to adhere to the inner surface of the pipe; a pressing process in which the pipe end is crushed to form the flat portion and the sealer applied in an annular shape is compressed and sealed; The present invention is characterized by comprising:

[0007] According to the method for sealing a pipe end of the present invention, the sealer is applied to the inner surface of the pipe in a ring shape using a nozzle, so that it can be adapted to various pipe diameters and the size and shape of the flattened portion formed at the pipe end. In addition, since the pressing process is performed after the sealer is cured, it is possible to prevent the mold and the like from being stained. Furthermore, at the stage where the sealer is applied to the inner surface of the pipe, the sealer is in an uncured state, and the sealer is firmly attached to the inner surface of the pipe by subsequent curing. Furthermore, the sealer is applied in a ring shape, so that the sealer is present all around the inner surface of the pipe. These make it possible to exhibit high sealing performance. Note that the circular portion whose cross section is kept circular is intended to be substantially circular, and includes, for example, a portion where the pipe is bent, or a portion that is slightly flattened due to the convenience of the product.

[0008] A preferred embodiment of the method for sealing a pipe end of the present invention comprises the steps of: In the application step, the sealer is applied to a position corresponding to the flat portion, In the pressing process, a portion of the sealer is shifted from the flat portion toward the gradually expanding portion while maintaining friction with the inner surface of the pipe due to adhesion between the sealer and the inner surface of the pipe, and the sealer is retained at the boundary between the flat portion and the gradually expanding portion to form a seal.

[0009] According to a preferred embodiment of the method for sealing a pipe end of the present invention, the sealer is crushed while part of it is adhered to the inner surface of the pipe. Therefore, the sealer is not simply crushed, but is displaced toward the gradually expanding portion while being deformed due to friction with the inner surface of the pipe. As a result, the sealer remains in the flat portion and at the boundary between the flat portion and the gradually expanding portion, and the pipe end can be effectively sealed.

[0010] A preferred embodiment of the method for sealing a pipe end of the present invention comprises the steps of: In the application step, the sealer is applied to a position corresponding to the gradually expanding portion, In the pressing step, the sealers facing each other on the inner surface of the pipe are brought into contact with each other to seal.

[0011] According to a preferred embodiment of the method for sealing a pipe end of the present invention, the conditions in the coating step can be controlled more gently, and the occurrence of defects can be reduced.

[0012] A preferred embodiment of the method for sealing a pipe end of the present invention comprises the steps of: The above-mentioned application step is performed by applying the sealer to a plurality of locations by shifting the sealer in the axial direction of the pipe.

[0013] According to a preferred embodiment of the method for sealing a pipe end of the present invention, sealers are provided at multiple locations, making the sealing more reliable.

[0014] A preferred embodiment of the method for sealing a pipe end of the present invention comprises the steps of: In the curing step, the sealer is semi-cured.

[0015] A preferred embodiment of the method for sealing a pipe end of the present invention comprises the steps of: The sealer has a cure time of at least 12 percent but less than 15 percent of the time to full cure.

[0016] A preferred embodiment of the method for sealing a pipe end of the present invention comprises the steps of: The sealer has a cure time of at least 15 percent but less than 22 percent of the time to full cure.

[0017] A preferred embodiment of the method for sealing a pipe end of the present invention comprises the steps of: The sealer has a cure time of at least 22 percent but less than 86 percent of the time to full cure.

[0018] According to the preferred examples of the method for sealing a pipe end of the present invention, the pipe end can be sealed with a high yield even under difficult sealing conditions. In addition, by setting appropriate curing conditions, it is possible to prevent mold contamination. Effect of the Invention

[0019] As described above, the pipe end sealing method of the present invention can prevent contamination of molds, etc., can accommodate various pipe diameters and shapes or sizes of flattened portions formed on the pipe end, and has excellent adhesion between the sealer and the inner surface of the pipe. [Brief description of the drawings]

[0020] [Figure 1] 1A and 1B are a front view and a longitudinal sectional view of a pipe sealed by a method for sealing a pipe end according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a plan view of the pipe shown in FIG. [Diagram 3] FIG. [Figure 4] FIG. 13 is a diagram illustrating a state after the coating process. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 13 is a diagram illustrating another embodiment. [Figure 8] FIG. 13 is a diagram illustrating an experiment to confirm the cured state of a sealer. [Figure 9] These are the results of an experiment to confirm the hardening state of the sealer. [Figure 10] These are the results of an experiment to confirm the hardening state of the sealer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a pipe end sealing method according to the present invention will be described in detail with reference to the accompanying drawings.

[0022] First, the structure of a pipe 1 formed by the method for sealing a pipe end of this embodiment will be described with reference to Figures 1 and 2. Figure 1(A) is a front view of a pipe 1 sealed by the method for sealing a pipe end of this embodiment, and Figure 1(B) is a longitudinal sectional view thereof. As shown in these figures, the pipe 1 is formed into a flat portion 10 located at the very end and having a plate shape, a gradually expanding portion 13 whose cross section gradually expands from the flat portion 10, and a circular portion 15 whose cross section is kept circular. In addition, a bolt hole 11 for fastening a bolt is provided in the flat portion 10. Note that the pipe end 2 is intended to be a portion that includes the flat portion 10 and the gradually expanding portion 13, and in some cases, also includes a part of the circular portion 15.

[0023] Next, an embodiment of the pipe end sealing method will be described. The pipe end sealing method of this embodiment includes a coating step, a curing step, a pressing step, and a hole-making step. In the coating step, as shown in FIG. 3, a sealer 21 is applied in a ring shape to the pipe inner surface 3 of the pipe end 2 using a nozzle 20 inserted from the cut 4. At this time, the pipe 1 can be rotated relative to the nozzle 20 to coat the sealer 21 as shown by the arrow a in the figure. In addition, the sealer 21 is preferably applied to a location that will become the flattened portion 10 after the pressing step. Then, as shown in FIG. 4(A), the sealer 21 is formed in a ring shape on the pipe inner surface 3. In addition, as shown in FIG. 4(B), the sealer 21 can be applied to a plurality of locations by shifting it in the axial direction of the pipe 1. In this case, the sealer 21 is preferably applied to a location that will become the flattened portion 10 after the pressing step.

[0024] The curing process involves leaving the sealer 21 applied to the pipe inner surface 3 for a certain period of time after the application process to harden and adhere to the pipe inner surface 3. This curing process forms a seamless adhesive surface as in the circumferential direction of the pipe inner surface 3, as shown in Figures 4(A) and (B). As for the curing time in the curing process, the sealer can be used after being completely hardened (sometimes simply referred to as "hardened"), or it can be used in a semi-hardened state. This is because it is preferable to use either completely hardened or semi-hardened depending on the shapes of the flattened portion 10 and the gradually expanding portion 13.

[0025] The reason for this distinction will be explained. When pursuing only reliable sealing of the pipe end 2, the most preferable sealer is in its raw state immediately after application. When the pressing process is performed with this raw sealer 21, there is almost no occurrence of sealing defects. However, the raw sealer 21 may splatter and adhere to the mold, etc., causing a decrease in the operating rate due to the need to clean the equipment, or the sealer 21 adhered to the mold may re-adhere to the product, causing subsequent painting to be repelled. Furthermore, when the sealer 21 adhered to the mold hardens, it may leave a mark on the pressed product.

[0026] In order to eliminate the above-mentioned problems, it is preferable to perform the pressing process after hardening the sealer 21. When this sealer is hardened, there is no particular problem in a product in which the boundary 12 between the flat portion 10 and the gradually expanding portion 13 as shown in FIG. 2 is a straight line, and the angle of the rising portion 14 of the gradually expanding portion 13 as shown in FIG. 1(B) is relatively gentle. However, if the boundary 12 has a complex shape such as a curve, the angle of the rising portion 14 of the gradually expanding portion 13 is steep, or a reinforcing rib is provided on the flat portion 10, and the sealing conditions are severe, there is a risk of sealing failure. In such a case, the occurrence rate of failure can be reduced by using the sealer 21 in a semi-hardened state.

[0027] Here, the hardened state of the sealer 21 will be described with reference to the tables shown in Fig. 9 and Fig. 10. In the experiment shown in Fig. 9, the sealer 221 was applied to the base sheet 30 as shown in Fig. 8(A), and the appearance and the state of touching were observed after that. In the experiment shown in Fig. 10, the base sheet 30 was folded in half and pressed with fingers to make the sealers 221 stick together as shown in Fig. 8(B), so to speak, reproducing the state shown in Fig. 5(B), and the sealer 221 was cut and the cut surface was observed. In both Figs. 9 and 10, the temperature was 28.4°C and the humidity was 47.6% when the experiments were performed.

[0028] Here, the term "completely cured" refers to a state in which the surface of the applied sealer is no longer viscous and is hardened to a rubber-like state even when pressed firmly with a finger or a rod-shaped material. In this state, the sealer is almost completely viscous and is only elastic. The time required for this complete curing varies depending on the temperature and humidity at the time. For this reason, the time required for complete curing is expressed as 100% for convenience. In the case of semi-curing, the curing time is preferably 12% or more and less than 86% of the time required for complete curing. Furthermore, depending on the conditions for sealing, it can be 12% or more and less than 15%, 15% or more and less than 22%, or 22% or more and less than 86%. In the case of complete curing, the time is not limited to 420 minutes as shown in FIG. 9, and it can be several days after the sealer is fully cured. Therefore, when the sealer is used after being fully cured, it is not necessary to manage the time of the work in progress in a long time, which is advantageous in this respect.

[0029] The curing time (the time elapsed after the sealer 221 is applied) of 12% or more and less than 15% mainly refers to a state of 50 to 60 minutes in the tables of FIG. 9 and FIG. 10. The sealer 221 in this state is in a state where the surface has hardened a little, and when the base sheet 30 is folded in half and pressed with fingers, the sealer 221 does not become integrated, but remains stuck to each other. In addition, the sealer 221 is in a state where the viscosity is stronger than the elasticity, and when the sealer 221 is cut, the uncured part comes out from the cut surface. This is suitable for the pipe end 2 when the sealing conditions are the severest. Even if the pressing process described later is performed in this state, the hardened sealer 21 on the surface envelops the uncured sealer 21 inside like a rubber balloon expanding, so the mold and the like are hardly stained.

[0030] The curing time of 15% or more and less than 22% mainly refers to a state of 70 to 90 minutes in the tables of FIG. 9 and FIG. 10. The sealer 221 in this state has a surface that has hardened to some extent, and when the base sheet 30 is folded in half and pressed with fingers, the sealer 221 sticks to itself at first, but then peels off naturally. The sealer 221 has both elastic and viscous properties, and when the sealer 221 is cut, a small amount of uncured sealer comes out from the cut surface. This is suitable for the pipe end 2 when the sealing conditions are moderately severe. Even if the pressing process described later is performed in this state, the sealer 21 on the surface wraps the uncured sealer 21 inside as described above, and the sealer 21 is further cured, so that the mold or the like is not soiled.

[0031] A hardening time of 22% or more and less than 86% refers mainly to a state of 100 to 360 minutes in the tables of Figures 9 and 10. The sealer 221 in this state is generally somewhat hardened, and when the base sheet 30 is folded in half and pressed with fingers, the sealer 221 sticks slightly to itself, but then quickly peels off. Furthermore, the sealer 221 is in a state in which its elasticity is stronger than its viscosity, and even if the sealer 221 is cut, no unhardened part comes out from the cut surface. This is suitable for the pipe end 2 when the sealing conditions are somewhat severe.

[0032] Next, in the pressing process, the pipe end 2 is crushed to form the flat portion 10 and the gradually expanding portion 13, and the sealer 21 applied in an annular shape is compressed and sealed. This pressing process will be described with reference to Figs. 5(A)(B) and 6(A)(B). First, the sealers 21 facing each other on the pipe inner surface 3 as shown in Fig. 5(A) are close to each other, and then the sealers 21 are abutted against each other and crushed as shown in Fig. 5(B). At this time, since the sealer 21 is bonded to the pipe inner surface 3 by the adhesive surface as, when the sealers 21 applied in an annular shape are abutted against each other, they are crushed almost uniformly without shifting their positions. By crushing the sealer almost uniformly without shifting, it is possible to reduce the amount of sealer applied.

[0033] Next, as shown in FIG. 6(A), the sealer 21 is further crushed. At this time, the sealer 21 is crushed almost evenly because a part of the sealer 21 is fixed by the adhesive surface as between the sealer 21 and the pipe inner surface 3. It is also considered that the sealer 21 is fixed by the adhesive surface as, so that frictional force is generated between the sealer 21 and the pipe inner surface 3 in places other than the adhesive surface as, and the sealer 21 is deformed in a manner that combines shear deformation and elongation deformation. It is also considered that the sealer 21 is deformed and shifted while generating frictional force, so that the sealer 21 is shifted as if it is being rubbed against the pipe inner surface 3 with a strong force, improving the adhesion between the sealer 21 and the pipe inner surface 3, and improving the sealing yield.

[0034] Next, as shown in FIG. 6(B), when the pressing process is completed, a part of the sealer 21a remains at the boundary 12 between the flat portion 10 and the gradually expanding portion 13 in two lip-shaped layers, one above the other. The pipe end 2 is completely sealed by the upper lip portion 21a1 and the lower lip portion 21a2 formed by the sealer remaining at this boundary 12. At this time, in the flat portion 10a other than the adhesive surface as, although there are some parts where the sealer 21 is cut due to contact between the pipe inner surfaces 3, a very thin sealer 21 remains and connects the adhesive surface as and the sealer 21a at the boundary 12. As a result, the sealer 21a remains properly at the boundary 12 even after the product is completed, and stable sealing performance can be achieved. In addition, a part of the sealer 21b protrudes on the cut end 4 side of the pipe 1. As described above, this sealer 21b also remains thinly on the flat portion 10b other than the adhesive surface as and is connected to the adhesive surface as. This excess sealer 21b can then be removed using a tool such as a wire brush or a blade.

[0035] Next, the hole drilling process will be described. This hole drilling process is for forming bolt holes 11 for fastening bolts (see FIG. 1(B)). Here, the bolt holes 11 are formed in the flat portion 10 using a known die or the like.

[0036] Next, a pipe end sealing method according to another embodiment will be described with reference to Fig. 7. In this embodiment, in the application step, a sealer 121 is applied in a ring shape to a position corresponding to the gradually expanding portion 13. In this case, it is preferable to apply a larger amount of sealer 21 than in the embodiment in which sealer 21 is applied to the flat portion 10. Then, in the pressing step, the opposing sealers 121 on the pipe inner surface 3 come into contact with each other, sealing the pipe end 2.

[0037] As described above, according to the method for sealing a pipe end of this embodiment, the pressing process is carried out while the applied sealer 21 is in a cured or semi-cured state, so that uncured sealer 21 does not adhere to equipment such as molds, thereby improving the operating rate of the equipment.

[0038] In addition, as the sealer 21 hardens, an adhesive surface as is formed between the sealer 21 and the pipe inner surface 3. Since the sealer 21 and the pipe inner surface 3 are connected by this adhesive surface as, the sealer 21a that has deformed and shifted to the boundary 12 between the flat portion 10 and the gradually expanding portion 13 is also connected to the pipe inner surface 3, and stable sealing performance can be exhibited even after the product is completed. To explain this in more detail, the pipe inner surface 3, which is metal, and the upper lip portion 21a1, which is the sealer 21, are adhered by the upper adhesive surface as. Similarly, the pipe inner surface 3, which is metal, and the lower lip portion 21a2 are adhered by the lower adhesive surface as. And, the upper lip portion 21a1 and the lower lip portion 21a2 are in a state of being pressed against each other, but since they are sealers of the same material, they blend well together. In this way, different materials, namely the metal and the sealer, are adhered to each other, and the sealers of the same material are pressed against each other to exhibit high sealing performance.

[0039] In addition, the crushed sealer 21 spreads over the entire flat portion 10, preventing moisture and air from entering through the bolt hole 11. The sealer 21 in the flat portion 10 is also bonded to the pipe inner surface 3 by the adhesive surface as, and therefore undergoes a deformation that combines shear deformation and elongation deformation while maintaining friction with the pipe inner surface 3. Therefore, the sealer 21 remaining in the flat portion 10 can be made very thin while having excellent adhesion to the pipe inner surface 3. As a result, the thickness of the flat portion 10 does not change substantially when the flat portion 10 is fastened with a bolt, and it is possible to achieve both stable axial force of the bolt and high rust prevention performance.

[0040] Furthermore, in an embodiment in which the sealer 21 is applied to a position corresponding to the gradually expanding portion 13 during the application process, the conditions for the application process and the pressing process are lenient, and the pipe end 2 can be sealed without strict quality control.

[0041] The above-described pipe end sealing method is merely an example of the present invention, and the configuration can be modified as appropriate without departing from the spirit and scope of the invention. [Explanation of symbols]

[0042] 1 Pipe, 2 Pipe end, 3 Pipe inner surface, 4 Cut end, 10, 10a, 10b·· flat portion, 11·· bolt hole, 12·· boundary, 13·· gradually expanding portion, 14·· rising portion, 15·· circular portion, 20··Nozzle, 21, 21a, 21b, 121, 221··Sealer, as··Adhesive surface, 30...Base sheet,

Claims

1. A method for sealing a pipe end, comprising pressing the pipe end to form a plate-like flat section, a gradually expanding section whose cross section gradually expands from the flat section, and a circular section whose cross section is maintained circular, comprising: a coating step of applying a sealer in an annular manner to the entire circumference of the inner surface of the pipe at the end of the pipe using a nozzle; a curing step for curing the sealer to adhere to the inner surface of the pipe; a pressing process in which the pipe end is crushed to form the flat portion and the sealer applied in an annular shape is compressed and sealed; 13. A method for sealing a pipe end, comprising:

2. In the application step, the sealer is applied to a position corresponding to the flat portion, 2. A method for sealing a pipe end as described in claim 1, wherein, in the pressing process, a portion of the sealer is shifted from the flat portion toward the gradually expanding portion while maintaining friction with the inner surface of the pipe by adhesion between the sealer and the inner surface of the pipe, so that the sealer remains at the boundary between the flat portion and the gradually expanding portion to seal it.

3. In the application step, the sealer is applied to a position corresponding to the gradually expanding portion, 2. The method for sealing a pipe end according to claim 1, wherein in the pressing step, opposing sealers are brought into contact with each other on the inner surface of the pipe to seal it.

4. 4. The method for sealing a pipe end according to claim 1, wherein the application step comprises applying the sealer to a plurality of positions shifted in the axial direction of the pipe.

5. 5. The method for sealing a pipe end according to claim 1, wherein the sealer is semi-cured in the curing step.

6. 6. The method of claim 5, wherein the cure time of the sealer is greater than or equal to 12 percent but less than 15 percent of the time to full cure.

7. 6. The method of claim 5, wherein the cure time of the sealer is greater than or equal to 15 percent but less than 22 percent of the time to full cure.

8. 6. The method of claim 5, wherein the set time of the sealer is greater than or equal to 22 percent but less than 86 percent of the time to full cure.

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