Method for joining pipes and reinforced pipe manufactured by the same

Abstract

To provide a method for reinforcing pipes that enables mechanical joining with the same level of strength as welding, without welding or screwing, and reinforced pipes manufactured by the method.SOLUTION: A reinforcement pipe 2 with a smaller diameter than a main pipe 1 is inserted into the main pipe 1, and the main pipe 1 and reinforcement pipe 2 are joined by a burring process from the main pipe 1 to the reinforcement pipe 2. A barring section 3 is provided at several locations on the main pipe 1 in a longitudinal direction. The burring process may be performed at each location simultaneously, and the burring process may be performed on a front side and a back side of the main pipe 1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for joining pipes and a reinforced pipe manufactured by the method.

Background Art

[0002] When installing a fence in a place where strong winds are likely to blow, when installing a tall fence or when sharing a support for fences of different heights, sufficient strength is required for the support. Therefore, a reinforcement method may be adopted in which a reinforcing pipe is inserted inside the pipe serving as the support to increase the strength of the support pipe and, by extension, the strength of the fence.

[0003] When joining the support pipe and the reinforcing pipe in this method of making a double pipe, it is common to join the ends of both pipes by welding. However, in that case, the plating or painting of the pipe may be damaged by the heat associated with welding, and repair may be required. However, such repair not only takes time and costs, but may also not return to the original state and rust may occur. In addition, since the vinyl packaging cannot be done until the heat from welding cools down, there is also a problem that the packaging takes time.

[0004] As another support reinforcement method, bolt joining is conceivable. However, in that method, it is difficult to join the support pipe and the reinforcing pipe tightly without gaps, so the strength tends to be insufficient. In addition, since both pipes lack adhesion, there is a risk that the two pipes will collide with each other and generate contact noise after construction.

[0005] Furthermore, as another reinforcement method, there is a method of ensuring strength by increasing the thickness of the support pipe without using a reinforcing pipe. However, in that case, it is necessary to prepare a plurality of types of supports, and a plurality of types of fixtures for fixing fences or the like connected to the supports must be prepared and stored according to the size of the supports, so waste is likely to occur and there are cost problems.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-204939 [Patent Document 2] Japanese Patent Application Publication No. 7-301031 Summary of the Invention [Problem to be solved by the invention]

[0007] As mentioned above, conventional methods for reinforcing pipes to be used as pillars have had various problems. Therefore, the present invention aims to provide a pipe joining method that does not have such problems, i.e., a method that can achieve mechanical joining with strength equivalent to that of welding without relying on welding or bolting, and a reinforced pillar manufactured using this method. [Means for solving the problem]

[0008] To solve the above problem, the invention described in claim 1 is a method for joining pipes, characterized in that a second pipe having a smaller diameter than the first pipe is inserted into the first pipe, and the first pipe and the second pipe are joined by performing a burring process from the first pipe to the second pipe.

[0009] In one embodiment, the burring is performed at several positions in the longitudinal direction of the first pipe.

[0010] In one embodiment, the burring is performed simultaneously at a plurality of locations.

[0011] In one embodiment, the burring is performed on the front and back sides of the first pipe.

[0012] The invention described in claim 5, which solves the above problem, is a reinforced pipe characterized in that a second pipe having a smaller diameter than the first pipe is inserted into a first pipe, and the first pipe and the second pipe are joined by a method described in any of claims 1 to 4.

[0013] In one embodiment, the reinforcing pipe is a fence post. [Effects of the Invention]

[0014] The pipe joining method of the present invention and the reinforced pipe produced by that method are as described above. The method of the present invention has the advantage of being able to produce reinforced pipes with joint strength equivalent to that achieved by welding, without the problems that arise with welding, such as the adverse effects of heat on plating and paint, and without the problem of insufficient strength caused by screw fastening.The reinforced pipes produced by this method have sufficient strength, and therefore fences built using them as supports have sufficient strength to withstand strong winds. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a front view of a reinforced pipe according to the present invention. [Figure 2] 1A is an enlarged view of a burred portion of a reinforced pipe according to the present invention, and FIG. 1B is an enlarged view of line AA in FIG. 1A. [Figure 3] FIG. 2 is a diagram showing a test method carried out to confirm the strength of the reinforced pipe according to the present invention. [Figure 4] 1 is a diagram showing an example of a fence constructed using reinforced pipes according to the present invention as supports. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of the present invention will be described in detail with reference to the accompanying drawings. The pipe joining method according to the present invention is characterized in that a second pipe having a smaller diameter than the first pipe is inserted into the first pipe, and the first pipe and the second pipe are joined by burring from the first pipe to the second pipe. In many cases, the second pipe is inserted into the first pipe to reinforce the first pipe, so in the following description, the first pipe will be referred to as the main pipe 1 and the second pipe will be referred to as the reinforcing pipe 2.

[0017] In many cases, the reinforcing pipe 2 is inserted into the main pipe 1 to reinforce it, and has a shape corresponding to the main pipe 1, preferably with a diameter that allows it to slide against the inner surface of the main pipe 1. Also, the length of the reinforcing pipe 2 is usually shorter than that of the main pipe 1, for example, about half the length of the main pipe 1. The main pipe 1 and reinforcing pipe 2 shown in the figure are cylindrical, but they may also be rectangular pillars or other shapes.

[0018] The main pipe 1 and the reinforcing pipe 2 are tightly joined by burring. Needless to say, burring is a technique used when fitting a screw into a thin plate, as the thinner the plate, the weaker the fit. Therefore, by creating a cylindrical rise in the drilled portion, thickness is created to secure the thread, thereby strengthening the fit. Furthermore, although there are cases where an internal thread is cut into the cylindrical portion, in the method according to the present invention, it is usually sufficient to leave the cylindrical portion (burring portion 3) formed by burring as it is (in a cylindrically stretched state).

[0019] The burring process itself in the pipe joining method according to the present invention is performed by a general method. However, the portion to be burred is the lower side when the reinforcing pipe 2 is inserted into the main pipe 1 and set upright. Usually, several burring portions 3 are provided vertically side by side. At that time, in order to ensure the fixing strength and stability by burring, it is preferable to perform the burring process simultaneously at a plurality of locations (for example, all locations). In addition, burring may be performed not only on the surface side but also on both the front and back surfaces. After the burring process, the holes in the burring portion 3 are conspicuous, but since that portion is buried in the foundation, it will not be conspicuous after construction of a fence or the like.

[0020] In order to confirm the joining strength of the inner and outer double pipes 1 and 2 joined by the pipe joining method according to the present invention described above, the following tests were conducted. The test was conducted assuming that a reinforced pipe 10 provided with burring portions 3 at two locations each on the front and back of the pipe was used as a fence post.

[0021] A. Tipping test Assuming the construction time, a tipping test was conducted 3 times to observe the looseness of the reinforcement by tipping from a state of standing vertically with respect to the ground (Fig. 3(1)). B. Vertical drop test Assuming the construction time, a vertical drop test was conducted 3 times to observe the looseness of the reinforcement each time by dropping vertically from a position 0.3 m above the ground (Fig. 3(2)). C. Drop test Assuming the construction time, a drop test was conducted 3 times to observe the looseness of the reinforcement each time by rotating and dropping the other end side from a state of holding one end horizontally at a position 1 m above the ground (Fig. 3(3)). D. Repeated bending test Assuming a wind load, a test was conducted in which one end was fixed and the other end was repeatedly bent for 20 minutes (960 times) at a speed of one round trip in 2.5 seconds in the horizontal direction (Fig. 3(4)). E. Vibration durability test Assuming the transportation time, it was fixed on a vibration testing machine and a vibration durability test (JIS D1601) was conducted at a vibration frequency of 33 Hz for 40 minutes (about 79,000 times) (Fig. 3(5)).

[0022] As a result of the above tests, in all cases, there was no change in the fixed state of the reinforced pipe 10, i.e., the joint state between the main pipe 1 and the reinforced pipe 2, after the tests, and no rattle was observed, so the effectiveness of the joining method of the present invention and the reinforcing effect of the reinforced pipe 10 were fully confirmed.

[0023] The burring portions 3 are provided, for example, at two locations on each of the front and back surfaces as described above, but the number of burring portions 3 can be increased or decreased depending on the length of the main pipe 1. Furthermore, it is preferable to provide the burring portions 3 in pairs on the front and back surfaces, but they may also be provided offset from each other, or on only one of the front and back surfaces.

[0024] As described above, the pipe joining method of the present invention involves fixing the pipes by burring alone, but burring crimping may also be performed. Burring crimping is a processing method in which the cylindrical portion is crushed and crimped after burring, which further increases the fixing strength.

[0025] The reinforced pipe 10 manufactured using the pipe joining method of the present invention can be used, for example, as a fence post (see FIG. 4). The strength of the reinforced pipe 10 is sufficient, as evidenced by the above test results, and so it can be used suitably for fences of any size. While strength was previously ensured by varying the pipe diameter to match the fence size, using the reinforced pipe 10 as a post eliminates the need to stock pipes of various diameters in advance, offering significant advantages in terms of cost and storage.

[0026] When the reinforced pipe 10 is used as a fence post, as mentioned above, the burring portion 3 is hidden in the foundation and is not exposed. In addition, concrete or the like flows into the pipe through the burring portion 3, which increases the stability of the post. [Industrial Applicability]

[0027] The pipe joining method according to the present invention and the reinforced pipe manufactured by this method are as described above. According to the method of the present invention, problems caused by welding, such as the adverse effects of heat on plating and painting, are eliminated, and there is also no problem of insufficient strength due to screwing. There is an effect that a reinforced pipe having a joining strength equivalent to that of welding can be manufactured. The reinforced pipe manufactured by this method has sufficient strength. Therefore, a fence constructed with it as a support has sufficient strength to withstand strong winds, and its industrial applicability is great.

Explanation of Signs

[0028] 1 Main pipe 2 Reinforcing pipe 3 Beveling part 10 Reinforced pipe

Claims

1. A pipe joining method, characterized in that a second pipe having a smaller diameter than the first pipe is inserted into the first pipe, and the first pipe and the second pipe are joined by performing a burring process from the first pipe to the second pipe.

2. The pipe joining method according to claim 1, wherein the burring process is performed at several locations in the longitudinal direction of the first pipe.

3. The pipe joining method according to claim 2, wherein the burring process is performed at a plurality of locations simultaneously.

4. The pipe joining method according to claim 1, wherein the burring process is performed on the front surface side and the back surface side of the first pipe.

5. A reinforced pipe, characterized in that a second pipe having a smaller diameter than the first pipe is inserted into the first pipe, and the first pipe and the second pipe are joined by the method according to any one of claims 1 to 4.

6. The reinforced pipe according to claim 5, wherein the reinforced pipe is a fence post.

Images