JPH0739037B2 - Pipe joint structure and pipe joining method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pipe joint structure in which two pipes having the same diameter or different diameters are joined in a substantially T-shape, and the two pipes are joined in a substantially T-shape. The present invention relates to a method for joining pipes.

[Conventional technology]

Conventionally, the following various structures have been known as a joint structure in which two pipes are joined into a substantially T-shape by welding, such as the parts A and B of the sidewalk shown in FIG. There is.

That is, as shown in FIGS. 7A and 7B, the end surface 7 of the joint pipe 2 is pressed against the outer peripheral surface 8 of the mother pipe 1, and in this state, the mother pipe 1 and the joint pipe 2 are joined by welding. As shown in FIGS. 8 (a) and 8 (b), the end surface 7 of the joint pipe 2 preliminarily processed along the outer peripheral surface 8 of the mother pipe 1 is pressed against the outer peripheral surface 8 of the mother pipe 1, In this state, the mother pipe 1 and the joint pipe 2 are joined by welding.
As shown in FIGS. (A) and (b), a hole 9 having a diameter larger than the outer diameter of the joint pipe 2 is formed in the peripheral wall of the mother pipe 1, and the end portion 5 of the joint pipe 2 is inserted into the hole 9, It is known that the mother pipe 1 and the joint pipe 2 are joined by welding in this state.

On the other hand, as a method of welding the mother pipe 1 and the joint pipe 2, arc welding and resistance welding are generally used,
Resistance welding is superior to arc welding in mass productivity and can be used for curved surfaces without advanced welding skills, and it can be automated using robots without the need for expensive equipment investment to maintain workpiece accuracy. It is known that there is an advantage that can be achieved.

[Problems to be Solved by the Invention]

Each of the conventional joint structures described above has the following drawbacks.

That is, in the structure shown in FIGS. 7 (a) and 7 (b), the outer peripheral surface 8 of the mother pipe 1 is a curved surface, whereas the end surface 7 of the joint pipe 2 contacting the outer peripheral surface 8 is a flat surface. 1 has a drawback that the contact area between the pipe 1 and the joint pipe 2 is small and the joint strength is small. In the structure shown in FIGS. 8 (a) and 8 (b), in order to make the end surface 7 of the joint pipe 2 along the outer peripheral surface 8 of the mother pipe 1, the end surface 7 of the joint pipe 2 is curved or ground. It has to be applied, which has the drawback of increasing costs. Further, in the structure shown in FIGS. 9 (a) and 9 (b), since the outer peripheral surface 6 of the end portion 5 of the joint pipe 2 and the peripheral edge 10 of the hole 9 of the mother pipe 1 are not in contact with each other, resistance welding may be used. However, there is a drawback that arc welding, which is inferior in mass productivity to the resistance welding, must be used. Moreover,
For example, in a place where a large load is applied, such as the portion A in FIG. 6, the entire space between the outer peripheral surface 6 of the end portion 5 of the joint pipe 2 and the peripheral edge 10 of the hole 9 of the mother pipe 1 is secured in order to secure the joining strength. It is necessary to perform arc welding over the circumference, and there is a drawback that the cost is significantly increased. Further, for example, in a place where a load is not so much applied as in the portion B of FIG. 6, there is no problem in strength even if partial welding is performed, but after welding, a gap is left in a place where welding is not performed, and the appearance is There is a problem that water is damaged or rust occurs when water enters through the gap.

In view of the above circumstances, the present invention provides a pipe joint structure that has a good appearance, does not cause rust, and has high joint strength, and also provides a pipe joint method that can obtain the joint structure at low cost. Is what you are trying to do.

[Means for Solving the Problems]

The pipe joint structure according to the present invention is a pipe joint structure in which a mother pipe having a substantially circular cross section and a joint pipe are joined to each other in a substantially T-shape by welding, wherein the mother pipe has a flat portion on a peripheral wall thereof. While having a hole having an inner diameter smaller than the outer diameter of the joint pipe formed in the flat portion, the joint pipe,
The mother pipe has an end portion corresponding to the shape of the hole of the mother pipe, the outer diameter of which is smaller than the inner diameter of the hole of the mother pipe, and the end portion of the connecting pipe is the mother pipe. Of the connecting pipe, and resistance welding is applied to the contact portion between the mother pipe and the connecting pipe in a state where the outer peripheral surface of the end portion of the connecting pipe is aligned with the peripheral edge of the hole of the mother pipe. Is.

On the other hand, the pipe joining method according to the present invention is a pipe joining method in which a mother pipe and a joint pipe having a substantially circular cross section are joined to each other in a substantially T-shape by welding. Form a small hole, and flatten the periphery of this hole, so that the end of the joint pipe fits the shape of the hole of the mother pipe, and the outer diameter of its tip is smaller than the inner diameter of the hole. It is formed so as to be tapered so as to be small, the end portion of this connecting pipe is inserted into the hole of the mother pipe, and the mother pipe and the connecting pipe are formed by aligning the outer peripheral surface of the end portion of the connecting pipe with the periphery of the hole of the mother pipe. After being combined into a T-shape, resistance welding is applied to the contact portion between the mother pipe and the joint pipe.

In this method, it is preferable that the hole of the mother pipe is formed by punching and at the same time the periphery of the hole of the mother pipe is flattened by pressing.

[Action]

According to the configuration of the pipe joint structure of the present invention, since the outer peripheral surface of the end portion of the joint pipe and the peripheral edge of the hole of the mother pipe are joined over almost the entire circumference, the appearance is good and the joint strength is high. Becomes

On the other hand, according to the configuration of the pipe joining method of the present invention, when the mother pipe and the joint pipe are combined, the outer peripheral surface of the end portion of the joint pipe is in contact with the peripheral edge of the hole of the mother pipe over substantially the entire circumference. Therefore, even if resistance welding is used as the welding method, the mother pipe and the joint pipe can be joined with sufficient joining strength. Also, since the end of the connecting pipe is tapered, the connecting pipe can be set in the mother pipe simply by inserting the end of the connecting pipe into the hole of the mother pipe, and the size of the hole of the mother pipe is Even if it is slightly misaligned, the outer peripheral surface of the end portion of the joint pipe can be reliably brought into contact with the peripheral edge of the hole of the mother pipe over substantially the entire circumference.

Furthermore, if the holes of the mother pipe are formed by punching and at the same time the peripheral edges of the holes of the mother pipe are made flat by pressing, the processing cost can be reduced and the appearance after joining will be good. Become.

〔Example〕

1 (a), (b) to FIG. 4 show an embodiment of a pipe joining method according to the present invention. In these figures, 1 is a mother pipe, 2 is a joint pipe, and each has a circular cross section.

In this pipe joining method, first, the mother pipe 1 and the connecting pipe 2 are configured as shown in FIGS. 2 to 4. That is, in the mother pipe 1, a circular hole 3 having a diameter a smaller than the outer diameter d of the joint pipe 2 is formed on the peripheral wall thereof, and the peripheral edge 4 of the circular hole 3 is laid flat. When forming the hole 3, for example, a punch having a flat pressurizing portion is applied to the peripheral portion to form the hole 3
It is preferable that the peripheral portion of the hole 3 is formed flat by the pressing portion at the same time as the punching is performed by the punch. If you do this,
The hole 3 is less likely to be distorted as compared with the case where the work of providing the hole 3 and the work of flattening the peripheral portion thereof are performed separately, so that the appearance after joining is improved and the work man-hour is reduced to process the work. The cost can be reduced. On the other hand, the joint pipe 2 has its end portion 5 fitted to the shape of the hole 3 of the mother pipe 1, that is, has a circular cross-sectional shape, and the outer diameter b of the tip is smaller than the diameter a of the hole 3. Tap to narrow it down.

Subsequently, the mother pipe 1 and the connecting pipe 2 are connected to each other as shown in FIG.
Combine as shown in (b). That is, mother pipe 1
The end portion 5 of the joint pipe 2 is inserted into the hole 3 of the mother pipe 1, and the outer peripheral surface 6 of the end portion 5 is aligned with the peripheral edge 4 of the hole 3 of the mother pipe 1, so that the mother pipe 1 and the joint pipe 2 are T-shaped. Combine.

After that, resistance welding is applied to the peripheral edge 4 of the mother pipe 1 and the outer peripheral surface 6 of the end 5 of the pipe 2 that contacts the peripheral edge 4 to join the mother pipe 1 and the joint pipe 2.

The joint structure of the pipe thus obtained has the end portion 5 of the joint pipe 2 which is squeezed to match the shape of the hole 3 of the mother pipe 1.
Is aligned with the peripheral edge 4 of the hole 3 of the mother pipe 1, so that the outer peripheral surface 6 of the end portion 5 of the joint pipe 2 and the peripheral edge 4 of the hole 3 of the mother pipe 1 are joined over the entire circumference. Therefore, the appearance is excellent and the end portion 5 of the joint pipe 2 is
Water and the like do not enter the inside of the mother pipe 1 or the like from between the outer peripheral surface 6 and the peripheral edge 4 of the hole 3 of the mother pipe 1, and the generation of rust can be prevented.

Moreover, since the outer peripheral surface 6 of the end portion 5 of the joint pipe 2 is in contact with the entire circumference of the peripheral edge 4 of the hole 3 of the mother pipe 1, and the contact area between the mother pipe 1 and the joint pipe 2 is large, arc welding No
Even if resistance welding is used, the joint strength is high.

As described above, according to the structure of the pipe joining method,
It is possible to increase the contact area between the mother pipe 1 and the joint pipe 2 without performing curved surface cutting or curved surface grinding unlike the conventional structure shown in FIGS. Since the joining strength can be obtained, the mother pipe 1
And the joint pipe 2 can be joined at low cost. Also,
Since sufficient joint strength can be obtained even by using resistance welding, mass production is possible, high welding skill is not required, and automation using robots etc. can be achieved without expensive capital investment. become able to.

Further, this pipe joining method is performed by using the end portion 5 of the joint pipe 2.
Since the taper is narrowed, the connecting pipe 2 can be easily set in the mother pipe 1 only by inserting the end portion 5 of the connecting pipe 2 into the hole 3 of the mother pipe 1. Moreover, even if there is a processing error in the inner diameter a of the hole 3 of the mother pipe 1, since the end portion 5 of the joint pipe 2 is thicker toward the root, the insertion depth of the end portion 5 of the joint pipe 2 can be increased. If you adjust
The outer peripheral surface 6 of the end portion 5 of the joint pipe 2 is surely brought into contact with the peripheral edge 4 of the hole 3 of the mother pipe 1. Therefore, it is not necessary to process the hole 3 of the mother pipe 1 with high precision.

In addition, in the configuration of this pipe joining method, the hole 3 of the mother pipe 1 is punched, and at the same time, the peripheral edge 4 of the hole 3 of the mother pipe 1 is punched.
Has the following effects. That is, if the hole 3 is formed in the mother pipe 1 only by a drill or the like, the hole 3 in the mother pipe 1 is formed because the peripheral edge of the mother pipe 1 is curved as shown in FIGS. 5 (a) and 5 (b). A peripheral edge 4 is formed in a shape curved in the height direction. For this reason, when the end portion 5 of the joint pipe 2 is squeezed so that its cross-sectional shape is circular, only the small end portions in the axial direction of the peripheral edge 4 of the hole 3 of the mother pipe 1 are the ends of the joint pipe 2. The outer peripheral surface 6 of the portion 5 does not come into contact with the outer peripheral surface 6, and the joint strength is reduced. Therefore, in this case, after forming the hole 3, it is necessary to flatten the peripheral edge 4 of the hole 3 or to squeeze the end portion 5 of the joint pipe 2 into a complicated shape.
The processing cost becomes high, or when the mother pipe 1 and the joint pipe 2 are combined, the end 5 of the joint pipe 2 must be inserted into the hole 3 of the mother pipe 1 while aligning the direction of the joint pipe 2. Assembly becomes worse. Moreover, when the peripheral edge of the hole 3 is flattened after the hole 3 is formed, the hole 3 may be deformed to make it difficult to insert the joint pipe 2. On the other hand, according to this pipe joining method,
Since the peripheral edge 4 of the hole 3 of the mother pipe 1 becomes flat at the same time as the punching process, it suffices to squeeze the end portion 5 of the joint pipe 2 so that its cross-sectional shape becomes circular. The drawing process can be performed easily, and it becomes unnecessary to pay attention to the directionality of the joint pipe 2 when the mother pipe 1 and the joint pipe 2 are combined. Also, the appearance is improved.

As shown in FIGS. 7A and 7B, the mother pipe 1
Let D be the outer diameter of the, and the size of the gap between the mother pipe 1 and the joint pipe 2 Then, when h ≦ 1 mm, that is, when the mother pipe 1 is extremely thick with respect to the joint pipe 2, the hole 3 of the mother pipe 1 is formed by drilling, and then the peripheral edge 4 of the hole 3 is flattened. Alternatively, the contact area between the mother pipe 1 and the joint pipe 2 can be sufficiently secured without squeezing the end portion 5 of the joint pipe 2 into a complicated shape. Therefore,
In the above case, the hole 3 of the mother pipe 1 may be formed by drilling. However, although the assemblability is slightly deteriorated, even if h> 1 mm, the end portion 5 of the joint pipe 2 should be squeezed into a complicated shape that matches the shape of the peripheral edge 4 of the hole 3 of the mother pipe 1. Then, the hole 3 of the mother pipe 1 may be formed by drilling.

Further, if the hole 3 of the mother pipe 1 is formed in an elliptical shape having a long diameter in the longitudinal direction and the cross-sectional shape of the end portion 5 of the joint pipe 2 is formed in an elliptical shape, the mother pipe 1 and the joint pipe 2 have the same diameter. However, both 1 and 2 can be connected in a T-shape. The mother pipe 1 and the joint pipe 2 do not have to be combined in an orthogonal state. That is, the mother pipe 1 and the joint pipe 2
The end portion 5 of the connecting pipe 2 may be inserted into the hole 3 of the mother pipe 1 in a tilted state. In this case, the connecting pipe 2
Forming the end portion 5 of the cross section into an elliptical shape, or
The hole 3 of the mother pipe 1 is formed in an elliptical shape having a major axis in the width direction.

〔The invention's effect〕

The joint structure of the pipe according to the present invention, the outer peripheral surface of the end portion of the joint pipe and the peripheral edge of the hole of the mother pipe having a substantially circular cross section are joined over substantially the entire circumference, and thus the appearance is excellent, It is possible to prevent the generation of rust and has high joint strength.

The pipe joining method according to the present invention, a hole having a smaller inner diameter than the outer diameter of the joint pipe is formed in the peripheral wall of the mother pipe having a substantially circular cross section, and the periphery of this hole is flattened, and the end portion of the joint pipe is By squeezing so as to match the shape of the hole, when the mother pipe and the joint pipe are combined, the outer peripheral surface of the end portion of the joint pipe is in contact with almost the entire circumference of the peripheral edge of the hole of the mother pipe. ing. Therefore, after joining, an excellent pipe joint structure as described above can be obtained.
Moreover, resistance welding can be used as a welding method,
Mass productivity can be improved, high welding skill is not required, and automation can be achieved by using a robot or the like without expensive capital investment. Also, since the end of the connecting pipe is tapered, the connecting pipe can be easily set on the mother pipe, and the outer peripheral surface of the end of the connecting pipe can be set without machining the hole of the mother pipe with high precision. Can be contacted over substantially the entire circumference of the peripheral edge of the hole of the mother pipe, so that the assemblability can be improved and the processing cost can be reduced.

Furthermore, if the hole of the mother pipe is formed by punching,
Since the hole can be formed and the periphery of the hole can be flattened at the same time, the processing cost can be reduced and the appearance after joining can be improved.

[Brief description of drawings]

1 (a), (b) to FIG. 4 show an embodiment of a pipe joining method according to the present invention.
(B) is a transverse sectional view and a longitudinal sectional view of the joint structure of the pipe obtained by the method, FIGS. 2 and 3 are transverse sectional views and longitudinal sectional views before the joining, respectively, and FIG. 4 is a diagram before the joining. 5 (a) and 5 (b) are horizontal and vertical cross-sectional views showing another embodiment of the mother pipe, and FIG. 6 is a front view showing a sidewalk shelf in which a pipe joint structure is used. FIGS. 7 (a), 8 (a) and 9 (a) are longitudinal sectional views showing a conventional joint structure of a pipe, and FIG. 7 (b) is a transverse section of FIG. 7 (a). Fig. 8 (b) is Fig. 8 (a).
FIG. 9 (b) is a cross-sectional view of FIG. 9 (a). 1 ... Mother pipe, 2 ... Joint pipe, 3 ... Mother pipe hole, 4 ... Mother pipe hole periphery, 5 ... Joint pipe end, 6 ... Joint pipe outer peripheral surface .

Claims (3)

[Claims] 1. In a joint structure of a pipe in which a mother pipe having a substantially circular cross section and a joint pipe are joined to each other in a substantially T-shape by welding, the mother pipe is formed with a flat portion on its peripheral wall and the flat portion. While having a hole having an inner diameter smaller than the outer diameter of the joint pipe, the joint pipe corresponds to the shape of the hole of the mother pipe, and its outer diameter is smaller than the inner diameter of the hole of the mother pipe. As such, the end portion of the connecting pipe is inserted into the hole of the mother pipe, and the outer peripheral surface of the end portion of the connecting pipe is fitted to the peripheral edge of the hole of the mother pipe. A joint structure of a pipe, wherein resistance welding is applied to a contact portion between the mother pipe and the joint pipe in a closed state. 2. A method for joining pipes, wherein a mother pipe having a substantially circular cross section and a joint pipe are joined to each other in a substantially T shape by welding, a hole having an inner diameter smaller than an outer diameter of the joint pipe is formed in a peripheral wall of the mother pipe, And, while flattening the periphery of this hole, the end portion of the joint pipe is tapered so as to match the shape of the hole of the mother pipe and the outer diameter of its tip is smaller than the inner diameter of the hole. After forming, the end portion of this connecting pipe is inserted into the hole of the mother pipe, the outer peripheral surface of the end portion of the connecting pipe is aligned with the peripheral edge of the hole of the mother pipe, and the mother pipe and the connecting pipe are combined in a substantially T-shape, A method for joining pipes, wherein resistance welding is applied to a contact portion between the mother pipe and the joint pipe. 3. The method of joining pipes according to claim 2, wherein the hole of the mother pipe is formed by punching and the periphery of the hole of the mother pipe is flattened by pressing.