Constant displacement quality control method of steel rail flame welding heating and post-weld normalizing

Abstract

A constant displacement quality control method of steel rail flame welding heating and post-weld normalizing comprises the following steps: locking an upsetting oil cylinder by controlling a magnet valve and a pilot operated check valve on the stock cylinder oil circuit of the upsetting oil cylinder so that the longitudinal displacement of the steel rail keeps constant; simultaneously, detecting the retaining pressure of the upsetting oil cylinder in real time through a pressure sensor, and then calculating and obtaining the temperature of the steel rail according to the curve of the relationship between the preset welding temperature of steel rail and the longitudinal deformation resistance of steel rail; when the temperature of steel rail reaches the preset welding temperature, controlling a heating device to stop heating, carrying out upsetting pressure retaining shearing, air-cooled cooling and post-weld normalizing. The method is capable of automatically controlling the temperature of gas-pressure welding and pressure retaining and normalizing of steel rail in closed loop, thereby having few control input parameters, simple and convenient operation, accurate control for temperature, strong anti-interference, small error, high precision, good technical uniformity and repeatability, more stable and reliable welding quality, and high one-time welding success ratio.

Description

technical field [0001] The invention relates to a quality control method for air pressure welding and post-welding normalizing of rail transit seamless line rails. Background technique [0002] Rail gas pressure welding is a main method used for on-site rail welding in my country's seamless railway construction. It adopts the mixed combustion method of gas and oxygen to heat the two butt-joined rail end faces. After heating, upsetting, pushing and normalizing are carried out. After cooling, the rail welding is completed. In each process of gas pressure welding of rails, welding temperature and extrusion deformation during upsetting are key factors determining the quality of gas pressure welded joints. However, in the process of rail welding and normalizing, since there are heating devices and swinging devices next to the rail welding joints, the space is narrow, full of swinging flames, and the temperature at the joints is very high, it is almost impossible to directly measu...

AI Technical Summary

Problems solved by technology

The control scheme obtained through experiments cannot be automatically adjusted for changes in the heating environment or gas, and the control ability for temperature is low, and the control error is large.

[0004] 2) During the heating and normalizing process, if the gas flow rate changes and the heat input rate changes, the change cannot be automatically adjusted in time.

[0005] 3) The control involves many variables such as heating time, gas flow, rail pressure and displacement, etc. The control process is complex, difficult to control, and greatly influenced by human factors

[0006] In short, the heating temperature of the rail welding process is controlled by time, the ability to adapt to changes in the environment and gas flow is poor, the control accuracy is low, the rail cannot meet the required temperature in the key links of welding and normalizing, the welding quality is poor, and the failure rate high

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