Electric heating – Metal heating – For bonding with pressure
Patent
1990-09-25
1992-05-26
Shaw, Clifford C.
Electric heating
Metal heating
For bonding with pressure
219123, B23K 908
Patent
active
051170841
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to the pressure welding, and more specifically to a method for pressure welding with heating with an arc moving in magnetic field.
BACKGROUND OF THE INVENTION
A special problem arises in welding small-diameter pipes which cannot be rotated during welding, e.g. during installation of pipelines where it is necessary to ensure stability of welding quality with the achievement of high productivity. These pipes are welded nowadays mainly manually using coated electrodes, or welding is performed in shielding gases. The number of welded joints largely depends on the welder skill, quality of materials and welding conditions. A change in position of the welding zone on space during transition from the top point of the weld to the bottom point thereof complicates the process as it is necessary to correct welding conditions.
To avoid errors characteristic of the manual welding, microprocessor controlled welders are used in certain applications. This results in an increase in the number of welded joints and results in a certain improvement of productivity, the cost of welding equipment increases, and requirements imposed on skill of the operating personnel are more stringent, certain restrictions being imposed upon operating conditions of the equipment (e.g. ambient temperature, dust lading and humidity of air).
In certain applications a continuous flash butt welding is used which ensures stability of quality of welded joints with a high level of automation of the process. This welding method can be used both at factories and in the field. However, welded joints produced by this method are characterized by the presence of irregularly shaped flash having sharp projections and collars which forms on both outer and inner surfaces of the pipeline. The flash on the inner surface of the pipeline is to be removed as it reduces the cross-section thus causing resistance to fluids moving through the pipeline. The removal of such flash is generally carried out by means of cutting tools attached to a bar which is very difficult and can only be made at straight portions of the pipeline.
Methods of welding with an arc moving in magnetic field which are most promising and productive have recently come into use for welding small-diameter pipes.
Known in the art is a method for pressure welding with heating with an arc moving in magnetic field (DD, A, 129179), comprising placing parts being welded, e.g. pipes coaxially with each other with a working gap defined between their ends, a permanent magnetic field being created in the gap, and firing an electric arc which moves along the perimeter of the ends under the action of the permanent magnetic field. At the beginning of the process, the arc current is set up in such a manner that the ends of the parts being welded be heated to a temperature of plastic deformation, which is followed by a pulsed increase in the arc current and upsetting.
In the abovedescribed method, the time for heating the ends to the temperature of plastic deformation is set up in advance without taking into account eventual deviations of the arc current or dimensions of the parts being welded, e.g. diameter or wall thickness of the pipes being welded. This negatively affects stability of quality of welded joints. Such deviations are not taken into account either when a fixed value of the duration of a pulsed increase in the arc current is set up. In addition, the prior art method does not allow local changes in the gap caused by non-parallelism of the ends and their irregular shape to be determined. As a result, the resultant welded joint may have local defects.
Welding conditions, which are generally determined as a result of a number of trial weldings, should be varied in changing over for welding of parts of different size which involves much time and energy expeses.
Therefore, the prior art method for welding with heating with an arc moving in magnetic field cannot guarantee stability of quality of a welded joint.
Known in the art is a method for pressure welding of par
REFERENCES:
patent: 3484578 (1969-12-01), Sciaky
patent: 4319123 (1982-03-01), Pache et al.
ZIS-Mitteilungen (DDR, No. 10, 1982, s. 1051-1055).
Genis Igor A.
Ignatenko Vadim J.
Jumatov Viktor V.
Kachinsky Vladimir S.
Krivenko Valery G.
LandOfFree
Method for pressure welding of parts heated with an arc moving i does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for pressure welding of parts heated with an arc moving i, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for pressure welding of parts heated with an arc moving i will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-421893