Steel rod Surface Treatment Process for Elastic Rail Clip
Elastic Rail Clip made of spring bar is a kind of elastic part, which is combined with rail bolt and tie plate, called rail fastener. Bullet bar is one of the most important parts in high-speed railway coupler. According to the state Council's passenger dedicated line construction plan, during the 11th Five-Year Plan period, 9,800 km passenger dedicated lines will be built in China successively, and the annual demand of coupler market for passenger dedicated lines will reach 1.5 billion RMB. At the same time, the product renewal cycle of coupler system will be 8 ~ 10 a, and product renewal will also bring considerable and sustainable market prospects for the enterprise.
Rai fastener is an important part of the railroad track. The steel rail and rail sleeper are combined together by the rail fastener. The function of rail fastener is to fix the correct position of the rail, prevent the longitudinal and transverse displacement of the rail, prevent the rail from overturning, and at the same time provide the necessary elasticity, insulation performance, have certain ability to adjust the gauge and horizontal.
Steel Requirements for Elastic Rail Clip
Elastic rail fasteners multi-purpose in high-speed railway to the beijing-shanghai high-speed railway as an example, the raw material for 60 Si2CrA Φ 13 mm hot spring steel wire rod, qualified to play in order to ensure the production, raw material wire rod surface treatment must be conducted, then cutting, bending, such as heat treatment process.
Chemical Composition of 60Si2CrA Steel Used for Elastic Rail Clip
Article elastic fasteners with 60Si2CRA Φ 13 mm hot spring steel wire rod chemical composition shown in table above.
Surface Treatment of Elastic Rail Clip
The surface treatment flow of wire rod for elastic rail clip: loading → pickling 1→ pickling 2→ high-pressure water washing → washing 1→ washing 2→ neutralization → blanking. The manipulator will transport the wire rod to the pickling section, according to the pickling program stored in the automatic system, control the number of separate treatment and pickling in each tank, in order to pickling, rinsing and other processing of wire rod.
The technological process of rod surface treatment for elastic bar fastener is shown in Figure 1.
All pickling tanks are equipped with drain valves, level gauges, sampling valves, etc. Lime tank temperature is automatically controlled. Both pickling tanks and lime tank are equipped with overflow valves and piping to the accident pit.
Technical Requirements of Elastic Rail Clip
|Tensile Strength MPa||Yield Strength MPa||Elongation after Fracture %||Reduction of Area %|
The forklift will lift the wire rod to the feeding trolley at the coiling place. The feeding trolley will move to the C-hook of the production line according to the instruction, and the manipulator will hook the C-hook with the wire rod into the production line for automatic processing according to the program. The production line can realize automatic control or manual operation.
Pickling and High-pressure Water Washing
Pickling with hydrochloric acid at room temperature. The first tank USES the recovered acid of the second tank. The acid liquid contains a large amount of Fe2 +, and W (HCl) is 10%. The recovered acid has a good ability to remove oxide scale and rust, while its ability to corrode iron matrix is greatly reduced. The mass concentration of Fe2 + in the tank is 100 ~ 130 g/L. After pre-pickling according to the preset program for a certain period of time, the manipulator will transfer the wire rod to the next pickling tank, at this time, the wire rod immersed in the pickling tank under room temperature, further remove the wire rod surface residual oxide layer. The wire rod is pickled at a predetermined time. The second pickling tank can continuously add new acid according to the test results, w (HC1) is 12% ~ 20%.
At this point, the mass concentration of Fe2 + in the tank is about 200 g/L, and the oxidizing substances on the surface of the wire rod will be removed. The suction wall on one side of the treatment tank absorbs the acid mist produced by the pickling tank on the operation line, which is sent to the absorption tower by a fan for washing, absorption and treatment, and then discharged into the atmosphere through the chimney. The workshop environment is clean and the equipment is not easy to be eroded by the corrosive atmosphere. After pickling, the manipulator will transfer the wire rod to the third tank.
The tank is used for high-pressure spray cleaning. The surface of the steel wire is thoroughly cleaned by high-pressure water at room temperature. The residual oxide skin on the steel wire surface is fully washed by high-pressure water. The high-pressure nozzle is installed in the tank, and the water is transported through the high-pressure pump, with a water pressure of about 0.9 mpa. The used high-pressure flushing water is collected into high-pressure puddles for recycling, which improves the utilization efficiency.
To improve the cleaning quality, the entire nozzle is arranged around the rod. The tank is provided with a cover plate which can be opened by a hydraulic device so that the coils can be unloaded and unloaded in the tank. The cover remains closed during treatment.
Flushing of Elastic Rail Clip
After pickling the wire rod is washed by high-pressure water, the wire rod is transferred to the fourth tank for rinsing with the manipulator, and the water temperature is room temperature. Remove the mixed acid and partially loose iron oxide from the surface of the wire rod in the rinse tank and determine the residence time according to the operating procedure.
Lime neutralized wire rod is transported to the neutralization tank of pickling line after being cleaned in the rinsing tank. The wire rod is immersed in lime aqueous solution, and the residual acid on the surface of the wire rod is neutralized. The temperature of the neutralization tank is set at 80 ℃. The saturated steam is indirectly heated to the required temperature, which is controlled by the temperature detector in the tank. The steam pipe is heated through the automatic regulating valve.
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