Replacement and repair technology of slewing bearing2018-09-25 22:45:07

1. Preface

In the process of loading and unloading of gantry crane, it is difficult to avoid accidental centrifugal force and stress concentration when rotating and lifting operation, resulting in the damage of slewing bearing (the 40t bearing used in this paper is 132.50.1500.03K5). Due to the fact that the bulk cargo wharf of the Huanghua port is located on the surface supporting beam, the carrying capacity is 8t/. The replacement of the slewing bearing requires the separation of the upper and lower parts of the portal crane before taking out the bearing. The total weight of the upper part of the portal crane is about 350t. If the large crane is used, it will exceed the loading capacity of the wharf. If the floating crane is used to lease at least a thousand ton floating crane, the cost will be more than one million yuan. The most economical plan is to install the heavy-duty jack on the 4 support points of the portal crane slewing bearing, and at the same time, the height of the bearing can be raised to achieve the replacement and maintenance operation of the slewing bearing. However, such maintenance, the upper part of the portal crane is suspended, and it needs fastening to ensure safety. Windproof and solid stabilization is very important. Lifting process requires 4 jack lifting at the same time to avoid bias dumping. To achieve the above requirements, strict construction management plan and scientific replacement and maintenance process must be worked out.

2. Safety preparedness before construction

The risk of maintenance operation is mainly: the upper part of the upper part of the door is suspended without connection during the process of jacking up and falling down. Therefore, the weather has great influence factors. It is necessary to check the local accurate weather forecast and choose sunny and dry weather. In order to ensure the safety of the operation during the process of windstorm or other bad weather during the jacking process, various protective measures and emergency preparedness must be made. After the wind protection contingency plan is made, the maintenance work can be carried out. After the power transmission is confirmed, the power transmission operation must be carried out, and the accident of electric safety should be avoided. The jacking process must be below 5. When the wind is going on.

In the process of maintenance, we should clarify the responsibilities of the managers. We need to organize the relevant technical management personnel and maintenance units to participate in the maintenance work. We will arrange the maintenance equipment for the detailed arrangement of the machinery, tools and related procedures in the maintenance process, and make detailed arrangements according to individual division of labor.

3, slewing bearing replacement maintenance process

1. welding support and other prophase work.

(1) under the plane. Long distance isolation for maintenance area before operation. On the ground, we use 24# channel steel to splice the door shaped frame and the middle beam to weld the lifting lug of the hand hoist. When the machine is welded, both the bottom and the diagonal direction are all supported by channel steel and angle steel. The bearing frame should be replaced to avoid the inclination of the bearing.

(2) on board. The lifting support needs cutting large lifting lug, grinding and leveling, and welding the bottom with the same thickness and long support plate. 3 single lifting lugs are welded to the bearing frame. 2 lifting lugs are welded on the tail weight of the portal crane, and the lifting lugs of two rear support seats are used for pulling 10t hoist with oblique pulling.

(3) inside the slip ring. After high voltage power failure, remove the central slip ring and all control lines, seal the joints with thick waterproof adhesive tape, and mark them with marking paper. The center slip ring is wrapped with asbestos cloth to prevent damage to the line by welding and gas cutting. The inner, front, rear, left and right 4 point welding single chip lifting lugs are used to adjust the radial position of the new bearing. Remove the rotary anchorage and seal it with iron plate. Remove the 24 central lubricating oil pipes and fold them up. Cut the upper and lower ladder along the bearing to support the use of the upper and lower center slip rings (instead of mobile ladder). Check whether the other locations of the slip ring are completely dismantled or affect the bearing pull-out.

(4) positioning. Move the portal crane to the anchor position without affecting the loading and unloading operation position, connect the windbreak cable and anchor, and drop the wind protection iron wedge. The amplitude is adjusted to the maximum 43M position. The boom faces towards the shore side (installation location, while the wind direction of the pier is parallel to the boom, reducing the wind force on the door machine). Disassemble the rotary bearing bearing oil pan and clean the oil pan and bearing grease.

2. jacking insurance and testing

(1) the use of jacking money bolts. 80 sets of internal and external fixed bolts are removed. Due to the overtightening force, the longitudinal cutting nut can be cut by gas cutting and dismantled 2 times. For the first time, the internal and external 2/3 fixed bolts were dismantled for the first time. The remaining 1/3 bolts were removed before the wind was ready to wind up before being repaired, and the 1/3 bolts (M42 * 680) were worn outside the bolt holes while the jack holes were lifted before lifting.

(2) because Jack plays an important role in the jack up process, a total of 6 320t jack is required, of which 2 are reserved. Place the bottom of the jack flat to the top lifting base, then aim the top lifting seat. After all fixed bolts and upper and lower connections are dismantled, press the 4 Jack simultaneously to ensure that each jack is laborious and rises at the same speed, otherwise the replacement jack is replaced.

3. jack up process

Due to the risk of wind in the jacking process, it is necessary to ensure that the jacking is completed at the shortest time in the case of small enough wind.

The process of jacking is controlled by the person in charge of construction. 1 surveyors were set up inside and outside, each lifting 50mm for a measurement to ensure that the error is within 5mm. Jack up jack jack cylinder position plus crescent plate for pressure relief protection, jacking up after adjusting the length of the bolt. After adjusting the same plane, the next lifting will be carried out. Tighten the upper nut in the lifting process, leave the 50mm clearance between the lower nut and the big gear ring, lift the 40mm height at each top, unscrew the lower nut until the lifting height reaches the required height 282mm.

Use bracing blocks and cushion blocks inside the jacking support.