Crane because of long time overload operation, slewing gear has two teeth from the root of the tooth broken, can be welded repair OH.
The key technology of welding repair is to avoid hot crack and cold crack. The method of preventing crack in welding is to reduce the diffusion hydrogen content of weld, reduce the hardening tendency and heat input, and reduce the binding stress of welding.
Because of the large welding work and long grinding time, the repair process of the combination of implant and welding is selected as follows.
(1) Opening T-shaped groove
The T-Groove is opened with a corner grinder at the bottom of the broken tooth, the width of the teeth is the same as the tooth root width of the original tooth, and the width of the muzzle is 40mm, and the groove is deep 30mm. Then, with the angle grinder to trim the bottom and the circumference of the groove, the exact size of the T-groove is finally measured.
(2) Replace tooth
① according to the size of T-groove and the original tooth, make a replacement tooth, so that the bottom of the replacement tooth is in accordance with the T-shaped groove, the upper part is the original tooth shape, and then the replacement tooth is inserted in the open T-shaped groove, notice that the inserts are not too tight. Check the relative position of the inserted replacement tooth so that the dimensions of each part conform to the requirements. If the error is too large, to redo or repair, until the replacement of the teeth inserted after the size of the parts meet the requirements.
The ② is fixed with a countersunk head screw to replace the tooth. After replacing the teeth, the hand drill is drilled in the direction perpendicular to the top of the tooth two ten until the steel matrix is drilled, use 8. The drill bottom hole on the cast steel base is approximately 25mm and the M10 thread is drilled. Then, do the hole at the top of the tooth. Finally, the M10 internal hexagonal screw will be used to fix the replacement tooth.
① Open the Groove. After the replacement of tooth grafting, respectively, the tooth root and cast steel matrix on both sides of the Matrix on the V-shaped groove, depth of about 12mm.
② welding process material selection. In order to reduce the content of hydrogen diffusion in the weld, the welding material adopts the J557 electrode with good low hydrogen type and crack resistance.
③ welding process parameters. 3.2mm J557 electrode, welding current 110A, after each layer instead of 4mm J557 electrode, current 130~160a, Power polarity selection DC reverse.
④ welding. Bake the J557 electrode at 350 ℃ temperature before welding 1h; with flame to preheat to 300 ℃ or so, the use of continuous arc welding, multi-layer multi-channel welding, pay attention to the use of yellow mud before welding of the rest of the tooth surface; each welding electrode hammer The weld immediately, eliminate the stress, each weld to clean the hammer hit; when welding, pay attention to the interlayer temperature is not less than 300 ℃, until the weld to the height of the base of the open slope; after welding, the asbestos cloth is used to cover the thermal insulation 8h, Then, the welding place is repaired with a corner grinder.
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