Crane Rail Welding Process and Crane Rail Welding Procedure
According to the different types of crane rail, the length of each crane rail section varies from 6 to 25 meters. These crane rail sections need to be welded together and then installed on the roadbed plane. So what is the crane rail welding process? What crane rail welding procedure is needed in the rail welding process? Let’s introduce it to you next.
Crane Rail Welding Procedure
Crane rail welding procedure is divided into four main types, respectively called the flash butt crane rail welding, gas pressure crane welding, thermite crane rail welding and electric arc crane rail welding.
- The flash butt crane rail welding has fast welding speed and stable quality, but the equipment is more complicated, mainly suitable for crane rail welding in the factory.
- Gas pressure crane rail welding has a short welding time and good welding quality, eliminating the need for a high-power power supply. Due to the strict requirements on the end face treatment of the joint during welding, it is not suitable for ultra-long crane rail welding.
- The equipment required for thermite crane rail welding is simple and easy to operate, but its performance is poor, so the quality control of on-site welding needs to be strengthened.
- The electric arc crane rail welding is more suitable for on-site operation, and the hardness and wear resistance of the welded part can exceed the original rail.
Crane Rail Welding Process
The rail welding process is mainly divided into four steps, they are pre-weld preparation, crane rail welding, stress relief heat treatment and joint smoothing treatment.
Before welding the joint of crane rails, the oil, rust and other dirt on the end face should be carefully cleaned to facilitate the subsequent welding process. Materials such as welding equipment and welding rods should be prepared according to the crane rail welding procedure used.
In order to facilitate the welding, the end of the crane rail shall be padded up to a certain height in advance. The actual padding height depends on the crane rail specifications, such as crane rail sizes and crane rail material.
Crane rail welding
The crane rail welding should follow the sequence of rail bottom, rail waist and rail head. Welding needs to be done layer by layer, and finally repair the surrounding gap. Preheating both ends of the track at the same time, preheating and interlayer temperature control between 300-350 degrees. The current of 120A-130A should be used for rail bottom welding. After each layer of welding is completed, the slag must be clear before welding can be continued. The current value of rail waist welding is 130A-140A, welding upward from the lower waist, pay attention to slag removal. The rail head welding still uses a current value of 130A-140A, and finally repairs the weld around the weld point.
Stress relief heat treatment
The stress relief heat treatment on the end of the crane rail sections is an important measure to improve the crane rail welding quality. Stress relief heat treatment adopts gas welding nozzle to heat the rail head, rail waist and rail bottom repeatedly, so that the whole section of the rail is heated evenly. The stress relief heat treatment temperature should reach 620-650 degrees, and keep constant temperature for 20-30 minutes. Extending each 40MM from the center of the crane rail welding point is the range of stress relief heat treatment.
The smoothing treatment for the joint of crane rail
When the rail welded joint has been subjected to stress relief heat treatment and cooled to atmospheric temperature, the weld on the top and sides of the rail shall be smoothed. When the crane rail welding bulge is too large, use the grinding wheel polishing machine to polish it until the welding place is flush with the rail head, and finally polish the surface.
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