Method and system for welding railroad rails-2

Method and system for welding railroad rails-2

Ceramic Welding Backing | Ceramic Backing Welding| Ceramic Backing Taps

BACKGROUND OF INVENTION

When depositing the first layer of molten metal onto the top of the backing plate between the bottom ends of the rails certain difficulties have been encountered, these difficulties affect the appearance of the weld which is to be made in the field in a very short time. The advancing welding wire used in the root pass has heretofore been moved by a robotic control in a normal weave pattern where the welding wire moves back and forth between the rails as the wire progresses along the backing plate in the bottom of the gap. This procedure causes the arc to blow through the backing plate resulting in irregular undersurface for the root pass and certain malformations in the root pass. Such blow through occurs more easily when the wire is moved too rapidly and pulls away from the weld puddle. As the robotic control moves the electrode in a robotic weave axially along the root of the gap, the arc is not pointed toward the intersection between the end of the rail and the lower backing plate. This further results in certain irregularities at this intersection. This problem is accentuated due to the fact that the backing plate is a relatively thin sheet whereas the two spaced rails are massive pieces of metal. The arc blow through of the backing plate and the inability to actually have a blow through at the intersection between the plate and rail ends has presented substantial inconsistencies in the root pass of the previously performed process. These problems affect the appearance of the root pass which is a disadvantage when attempting to use this new welding process as a replacement for prior butt welding and arc welding processes used in the field.

The present invention is a method and system for depositing molten metal from an advancing welding wire controlled by a robot to form a root pass of weld metal in the bottom of a gap between the railroad rails which gap is closed by a backing plate that is between the rails and it will be described with particular reference thereto; however, the invention has broader applications and may be used in welding the ends of railroad rails having various types of lower backing plates or in other welding operations where a root pass between two heavy metal members is deposited on the top of a relatively thin backing plate or bridging element. The present invention produces a root pass which overcomes the disadvantages heretofore experienced in producing the root pass of railroad rails by melting the backing plates as metal is deposited along the backing plate.

In accordance with an aspect of the present invention, the normal robotic weave pattern heretofore used in the gap between the rails is modified to a pendulum weave wherein the advancing welding wire controlled by a robotic mechanism is swung back and forth between the two rail ends. In this manner, the welding procedure followed by the welding wire is controlled to first swing the wire between an angle pointing toward one rail end to an angle pointing toward the other rail end. After this swinging action, the robotic mechanism moves the welding wire as it points toward the intersection between the backing plate and a rail end in a longitudinal direction. This move is a short distance, often in the range of 2-3 mm when the welding wire is about 1.6 mm. Thereafter, the swinging action is accomplished in the opposite direction bringing the welding wire to a position pointing toward the opposite intersection between the backing plate and the opposite rail end. When in the second angular position, the welding wire is again shifted longitudinally to complete a cycle of movement. The cycle is repeated to define a selected path extending along the backing plate to deposit the root pass as the backing plate is melted at least on its upper surface. The backing plate defines a barrier that produces a smooth undersurface for the resulting joint created by the root pass. In accordance with this aspect of the invention, the robotic mechanism maintains the spacing of the wire holding torch above the backing plate at a constant distance during the swinging action of the welding wire carried by the torch. By using the pendulum action and maintaining a constant height above the backing plate, the welding wire produces a consistent root welding pattern.

Date: 2023-04-10     hits: 593    Return