JPS6033584B2 - Equipment for flash welding of pipes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an apparatus for flash welding of pipes which can be used for welding relatively large diameter pipes both under field conditions as well as under factory conditions, for example in the installation of mains pipelines. Regarding.

Existing equipment for flash welding pipes can be classified into one of three categories:

○｝ An external welding machine in which all mechanisms, including the welding transformer, are located outside the pipe to be welded.

{21 An internal welding machine in which the entire mechanism, including the welding transformer, is located inside the pipe to be welded.

'31 A combination welding machine in which the alignment mechanism and upset mechanism are housed inside the pipe to be welded, while the welding transformer and current contact mechanism are located outside the pipe.

External welding machines are recommended for welding relatively small pipes; if you want to weld large diameter pipes with an external welding machine, you will need equipment that is heavy and difficult to handle.

In the case of external welding machines, it is extremely difficult to inspect joints. Internal welding machines are recommended for welding large diameter pipes under both field and factory conditions when the welding machine is moved from one joint to another, such as in the installation of main pipelines. be done.

The size of internal welding machines is limited by the pipe diameter and therefore the highest quality design and construction is absolutely necessary, especially with regard to the welding transformer and current contact elements. Combination welders are generally recommended for welding medium diameter pipe (820 to 102 m) under factory conditions.

The mechanisms of this type of welding machine are both inside and outside the pipe, so the mechanisms and fittings are not easily accessible. Larger size is another disadvantage of combination welding machines. Therefore, an internal type welding machine is most suitable for flash welding large-scale pipes. U.S. Pat. No. 3,164,718 discloses an elongated support village designed to operate inside a pipe and equipped with an axially movable body and an axially movable body for clamping the pipe. A device for flash welding of pipes is taught, in which each dielectric body is connected to a welding transformer through a current conducting body.

This prior art device has a donut-shaped welded transformer located near the joint on one of the cylinders in the rare body, which cannot be moved in the direction of rotation.

The electrode jaws and the transformer are connected by a flexible busbar. The electrode jaws are circumferentially equally spaced and insulated from the device structure. In operation, since the pipe is never ideal either circumferentially or end-face, the flushing action is initiated only on some portions of the end-face of the pipe to be welded, ie, the parts closest to each other.

As the flash progresses, all end faces become aftertouched. As a result of this initial stage of flash action, the transformer is activated locally. That is, only some of the transformer windings are loaded, and these are the windings closest to the endfield where the flash occurs. Therefore, transformer power is dissipated piecemeal and the initial stage of the flash is extended too much. The duration of the initial flash stage affects the duration of the entire welding process, limiting the capacity increase potential of prior art systems. The present invention is based on the fact that, by changing the structure of the current introducing body, it is possible to provide an apparatus for flash welding of pipes designed to work inside the pipes, which is more productive and reliable in operation. It is based on the discovery of

The said object is designed to operate inside the pipe, and comprises an elongated support member equipped with a clamping body movable in the vertical direction and immovable in the vertical direction for clamping the pipe, said longitudinal body being The current introducing body has an electrode jaw connected to the welding transformer through the current introducing body, and according to the invention, the current introducing body is arranged within an annular clearance defined by an elongated support member and a axially immovable attachment body. 2 located at and insulated from each other
This is achieved by providing a device for flash welding of pipes, which is characterized in that it is in the form of two coaxial contact tubes.
Such a current introducing body is simple in construction and therefore increases the reliability of the device for flash welding of pipes.

With this current introducing body, the input from the welding transformer is reduced, the time of the initial flash stage is shortened, and the production capacity of the equipment for pipe flash welding is increased. The electrical connection of each contact tube with the electrode forehead is such that the same electrical connection can be maintained as the jaws move radially when clamping the pipe before welding and when releasing the pipe after welding. Preferably, it is realized by a flexible cable.

The invention will now be described by way of example embodiments with reference to the accompanying drawings.

1 and 2 of the accompanying drawings, a device 1 for flash welding of pipes has an elongated support member 3 which is housed inside a pipe 2 to be welded and whose longitudinal axis coincides with the axis of the pipe 2 to be welded. There is.

Coaxially on the elongated support member 3 is a donut-shaped welded transformer 4.
and attachment bodies 5 and 6 each having a hydraulic drive mechanism 7.
It is equipped with. Of these, the tightening body 5 is immovable in the vertical direction, but the tightening body 6 is movable in the axial direction. Furthermore, on the elongated support member 3 there is coaxially mounted a pipe flush and upset mechanism 8, which itself is equipped with a hydraulic drive mechanism 9 and can be moved in conjunction with the universally movable vertical body 6.

The device 1 can thus be moved along the inner surface of the pipe by means of a trolley 10' having wheels 11 driven by a suitable motor (not shown). Two bearing discs 12 and 13 are fixed at opposite ends of the elongated support member 3, between which three sleeve members 15, 16 and 17 are mounted at intervals along the backing 3 on a support loaf 14. is provided.

While the first and second sleeve members 15 and 16 are incorporated into the pipe cotton fittings 5 and 6, respectively,
The third sleeve member 17 is integrated into the pipe flash and upset mechanism 8. The clamping body 5, which is immovable in the direction of the ball, and the elongated support member 3 have an annular gap (cl) between them.
This is clearly seen in the drawings in that the sleeve member 15 is shown not in direct contact with the support member 3.

As seen in FIG. 1, the bearing disk 12 is arranged behind both the welding transformer 4 and the sleeve member 15 when viewed from the joint side, that is, the welding transformer 4 is located axially away from the joint of the pipe 2. It is provided adjacent to the side of the immovable clamping body 5.

The sleeve member 17 of the pipe flush and upset mechanism 8 is located close to the bearing disc 13 and connected thereto by a hydraulic drive mechanism 9. Mouse direction movable clamping body 6
A sleeve member 16 is interposed between the sleeve member 17 and the pipe fitting and is connected to the sleeve member 17 by a hydraulic drive mechanism 7 for moving it along the elongated support member 3. The pipe clamping body 5 has longitudinal bars 18 arranged equidistantly and symmetrically with respect to the longitudinal axis of the support village 3.
have. One end 19 of each lever 18 has a bearing disk 12
′ are pivoted so as to be rotatable in the radial direction,
The other end 21 is pivoted at 22 to the end of each expansion lever 23. The opposite end of the expansion lever 23 is pivoted at 24 to a portion 25 of the sleeve member 15 closest to the pipe fitting. The end 21 of the clamping bar 18 holds electrodes 26 which are connected to corresponding taps of the transformer 4 via current introducing bodies, as will be described later. The ball attachment body 6 that is movable in the ball direction has a similar design, and each cord attachment lever 27
The only difference between the pipe clamps is that one end 28 is pivoted at 29 to the sleeve member 17 of the flush and upset mechanism 8, and the opposite end 30 is pivoted to the end of the respective expansion lever 32 at 31. It is different from 5. Expansion lever 3
The opposite end of 2 is the sleeve member 1 closest to the pipe joint.
It is pivoted at 33 to a portion 34 of 6. The end 30' of the attached bar 27 is connected to a corresponding tap (different from the one connected to the electrode jaw 26) of the transformer 4 via a current introducing body corresponding to the description below. The electrode jaws 35 are held in place. The current introduction body that connects the corresponding taps of the welding transformer 4 to the electrode frames 26 and 35 is a vertically attached body 5 that cannot be moved in the vertical direction.
It consists of two contact tubes 36 and 37 extending into an annular gap defined by the support member 3 and the elongate support member 3.

Contact tubes 36 and 37 are mounted coaxially and are insulated from each other by an insulating liner 38. The welding of the contact tube on one side is similar to that of the welding transformer 4 (
3 taps on the other side.
electrically coupled to corresponding electrode jaws 26 and 35 through flexible cables as at 9 and 40;
The welding circuit is thus set during operation. In operation, the device is fed into one of the pipes 2 to be welded such that the pipe end is located between the jaws 26 and 35. The hydraulic mechanism 7 of the cotton-attached body 5 that cannot be moved in the vertical direction is energized, and the sleeve member 15 is moved over its support roller 14 to the support part village 3.
along the direction toward the joint. While the sleeve member 15 is driven along the support member, the lever 23 cannot move in translation with the sleeve member 15, but can only pivot about the sleeve member 15. As the lever 23 rotates, its relative position with respect to the support member 3 changes and the vertically attached bar 1
8 is expanded, thereby bringing the lever 18 closer to the inner surface of the pipe 2, and further movement of the sleeve member 15 in the same direction causes the jaws 26 to abut the pipe and clamp it in place, aligning the alignment of the device and the pipe. . The other pipe is then slid over the free end of the device until it meets the end face of the previous pipe. This pipe is clamped by the pipe vertical body 6 in a similar manner to the clamping of the previous pipe. At the same time as the other pipe is clamped, the end faces of the two pipes are aligned, and the center of the machine is aligned with the axis of the pipe. Next, power is supplied to the welding transformer 4, and the pipe
The flush and upset mechanism 8 is energized to drive the pipe clamp 6 and the pipe clamped thereto in the direction of the other pipe. Here, current from the secondary winding of the welding transformer 4 is applied to the joint, and the contact tubes 36 and 37
, an electrical circuit is thus set up that includes the flexible cables 39 and 40 and the jaws 26 and 35. Since the end faces of pipes usually have irregular surfaces, the contact area will melt until the entire end face is melted and the flash is complete.
After that, the upset mechanism 8 performs the upset. During the course of the flash action, the contact tube acts as a current integrator as well as a current distributor to supply the current to the required parts of the joint at the required points in the flash action, thereby intensifying the flash and thus reducing the initial stage of the flash. is shortened.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a pipe flash welding apparatus embodying the concept of the present invention, and FIG. 2 is a sectional view taken along the row 0 line in FIG. 1. 3... Elongated support member, 4... Welding transformer, 5... Vertical body that cannot be moved in the axial direction, 6... Clamping body that is movable in the axial direction, 26. ...Electrode jaw, 35...
...Electrode jaw, 36...Contact tube, 37...
... Contact tube, 39 ... Flexible cable, 40
・・・・・・Flexible cable. Figure 1 Figure 2

Claims (1)

Claims: 1. An elongated support member designed to work inside a pipe and equipped with an axially movable clamping body 6 and an axially immobile clamping body 5 for clamping the pipe. 3, each of said clamping bodies having electrode jaws (26 and 35) connected to the welding transformer 4 through a current introducing body, wherein said current introducing bodies are electrically connected to each other. two coaxial contact tubes (36
and 37) A device for flash welding of pipes, characterized in that it has the shape of: 2. According to claim 1, each contact tube (36 and 37) is electrically coupled to the electrode jaws 26 and 5 by a flexible cable (39 and 40). The device described.