Slewing large gear welding repair method

Slewing large gear welding repair method
Crane overload operation for a long time, the rotating big gear two teeth broken from the tooth root can be welded repair.
The key technology of welding repair is to avoid hot cracking and cold cracking. The way to prevent cracks in the welding is to reduce the diffusible hydrogen content of the weld, to reduce the hardened tendencies and heat input and reduce welding restraint stress.
Longer grinding, welding workload due to the the surfacing whole toothdry transformers repair process was chosen following planting teeth and welding combined.
(1) open T-slot
The same as the first broken teeth using angle grinder or the like opening at the bottom of the T-shaped groove, the width of the tooth root of its upper opening width of the original tooth, under the mouth width than the upper opening width of 40mm, and the groove depth is 30 mm. Then, using angle grinder to the groove bottom and the surrounding grinding the flat, the last measure out the exact dimensions of the T-shaped slot.
(2) system replaces teeth
① According to the T-shaped groove and the dimensions of the original tooth, made a replacement tooth, to coincide with the T-shaped groove at the bottom of the replacement tooth, the upper part of the original tooth shape, and then to replace the tooth inlay T-shaped groove, open a good Note inserts seeded Do not overtighten. Check inlaid into the relative position of the replacement tooth, so that the size of the various parts to meet the requirements. If the error is too large to redo or trimming until the replacement teeth are mounted stud welding machineon the dimensions of the various parts of the compliance requirement.
(2) with countersunk screws fixed replacement teeth. After the replacement tooth inlay good hand DRILL drill two holes 10. 2mm in the vertical direction of the tooth top surface, position, respectively, from the center point of each 20mm of the both end surfaces of the teeth, until the drill into the cast steel base body until, then switch 8 . 5mm drill in the cast matrix drill the bottom hole depth of about 25mm and tapping M10 thread. Then, at the location of the tooth top well counterbore. Finally, with M10 socket head cap screws to replace teeth fixed.
(3) Welding
① open beveling. Replacement tooth explants good, respectively, in the tooth root and at the junction of the cast steel base body on both sides of the base body to open the V-shaped groove, a depth of about 12mm.
(2) the selection of the welding process material. In order to reduce the content of diffusible hydrogen in the weld, the welding material selection, better low-hydrogen and crack resistance J557 electrode.
(3) welding parameters. A bottom to choose 3. 2mm J557 welding rod, welding current 110A Stud welding systemsubsequent layers switch 4mm J557 electrode, current 130 ~ 160A, the power polarity selection DCRP.
Weld ④ facilities. J557 electrode in a temperature of 350 ° C before welding baking 1h; flame will be welded preheated to 300 ℃; vertical welding with arc, multi-layer multi-pass welding with Wong, etc. Note that before welding painted to cover the rest do not the welded tooth surface; finished welding a welding rod, immediately hammering the weld bead, eliminate stress, each weld bead must clean up hammering; Note that the inter-layer welding temperature not lower than 300 ° C until the solder to the open groove the height of the matrix; welding after asbestos cloth covered with insulation slow cooling 8h after finishing with angle grinder grinding welding.