Electric heating – Metal heating – By arc
Patent
1998-02-25
2000-05-09
Ryan, Patrick
Electric heating
Metal heating
By arc
219 60R, 219 61, B23K 912, B23K 902, B23K 3102
Patent
active
060606886
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a device for internally butt-welding pipes of the type including a support and guide frame for an annular welding member rotatable coaxially to the pipes to be welded and carrying a plurality of welding units each including support means for a spool on which the welding wire is wound, the support means being removably connected to at least a wall of a support frame of the welding unit so as to enable the support means to be replaced and spools of different type to be used, and including a brake for the spool.
BACKGROUND OF THE INVENTION
Known devices of the aforesaid type use a spool of special dimensions, different from those of the spools usually used for the external welding of pipes. This has resulted in numerous problems up to the present time, mainly the fact that two different spool types have to be constantly available, resulting in supply and stocking problems, spools for internal welding being moreover not always easily available as they are of special type. These spools are also of relatively high cost compared with the spools usually used for external welding.
Replacing the spool is also relatively lengthy and complicated.
As a matter of fact, in the known devices to change a spool first the welding units have to be removed from their welding position to a replacement one and then the spool and, generally also the attached brake, may be removed.
It is to be noted that to obtain a good welding a correct position of the welding units is essential and therefore after a change of a spool the position of said units has to be checked and adjusted.
Checking or adjusting the welding wire feed means is not easy in the known devices because also for this operation welding units have to be removed from their welding position in order to perform said controls, and this causes the drawbacks mentioned before.
Moreover in most devices the configuration of the joints of the brake coaxial to the spool exposes it to frequent damage because to remove the spool the brake must generally also be removed.
U.S. Pat. No. 3,551,636 describes a device for internally butt-welding pipes wherein each of the welding units comprises a spool on which welding wire is wound and which is mounted with its axle fitted into support notches in the rear ends of a wire supply trailer frame. The trailer frame is pivotally attached to a movable drive frame of the device. A brake may be applied to the spool. In this case, when a spool is empty and has to be removed from its support notches, also the brake is removed. Therefore, it is necessary to use special spools incorporating a brake or else detach the brake from the empty spool and mount it on a new one.
In known devices of the aforesaid type the welding wire feed means also have considerable drawbacks.
This means comprise a motor of particularly sophisticated and costly type, together with two reduction gears, one epicyclic and the other angular.
Although the known feed means are highly efficient they have proved difficult to assemble and maintain, and are also of extremely high cost.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the present invention is to provide a device for internally butt-welding pipes, in which replacing the spools of the welding units is simplified and does not need the movement of the welding units from their welding position.
A further object is to provide a device which enables spools of any type to be used.
A further object is to provide a device in which the welding wire feed means may be checked or adjusted without moving the welding units from their welding position.
A further object is to provide a device in which the spools of welding wire may be removed without removing also the brake of the spool.
A further object is to provide a device in which the wire feed means are easy to assemble and maintain and are of low cost.
These and further objects which will be apparent to an expert of the art are attained by a device in accordance with the present invention which includes a device for interna
REFERENCES:
patent: 3461264 (1969-08-01), Nelson et al.
patent: 3551636 (1970-12-01), Nelson
patent: 4306134 (1981-12-01), Slavens et al.
patent: 4483490 (1984-11-01), Engmann et al.
Dey Anjan
PSI Pipeline Service S.A.
Ryan Patrick
LandOfFree
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