Steel pipe offline quenching production device and method

Abstract

The invention discloses a steel pipe offline quenching production device and method. The production device comprises an external spray cooling device and an internal spray cooling device, the internalspray cooling device performs internal axial flow injection cooling on a rotating steel pipe, the external spray cooling device performs external spray pressurized spray cooling on the rotating steelpipe (10), the external spray cooling device comprises a direct spray cooling device (7), a steel pipe thickened end oblique spray cooling device (8) and a pressing wheel water supplementing device (9), the direct spray cooling device comprises a plurality of spray boxes, the front end of each spray box is provided with multiple rows of nozzles, the rear ends of the spray boxes are connected withwater inlet pipes, flow meters and flow regulating valves are installed on the water inlet pipes, the flow meters and the flow regulating valves are connected with controllers, the steel pipe thickened end oblique spray cooling device comprises a spray box, the front end of the spray box is provided with multiple rows of nozzles, a plurality of inner cavities are arranged in the spray box, each inner cavity is connected with a water inlet pipe, a flow meter and a flow regulating valve, and an angle is formed between the spray box of the oblique spray cooling device and the spray boxes of thedirect spray cooling device.

Description

technical field [0001] The invention relates to a steel pipe heat treatment technology, in particular to a production device and method for off-line quenching of a steel pipe. Background technique [0002] There are four main processes on the steel pipe heat treatment line: heating in the quenching furnace, water quenching, heating in the tempering furnace, and thermal straightening. The device generally adopts low-pressure water spraying method. [0003] However, water quenching often becomes the bottleneck process. The main reason is that the water quenching external cooling equipment currently used, whether it is a slit or a spray pipe, generally adopts a fixed low-pressure water spray device, and its cooling capacity is limited, even if the flow rate is increased. Effectively increase the cooling rate, so that the time required for water quenching of the steel pipe is much longer than that of other processes, resulting in low production efficiency, long time for the pip...

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Problems solved by technology

[0003] However, water quenching often becomes the bottleneck process. The main reason is that the water quenching external cooling equipment currently used, whether it is a slit or a spray pipe, generally adopts a fixed low-pressure water spray device, and its cooling capacity is limited, even if the flow rate is increased. Effectively increase the cooling rate, so that the time required for water quenching of the steel pipe is much longer than that of other processes, resulting in low production efficiency, long time for the pipe material in the furnace, serious surface oxidation, and high energy consumption

[0004] When tempering by internal spraying and external spraying, even if the flow of fixed low-pressure external spraying water can be adjusted in the length direction, since it is difficult to break the water film, there is little difference in cooling speed on the outside, while the internal spraying water flows from one end of the steel pipe to the other. At one end, the cooling rate difference of the inner surface is large, which leads to the difference of cooling rate at different positions of the steel pipe, which leads to large fluctuations in the strength of the steel pipe after quenching and tempering. The strength fluctuation of the whole steel pipe is generally 80~150MPa, and some pipe materials are bent after water cooling If it is too serious, the straightness of the pipe material still exceeds the standard after straightening, and it needs to be reprocessed again, which increases the production cost

[0005] For low-carbon series line pipes and structural pipes, which require a slow cooling rate and only a small flow rate, the external water spray will be very uneven under a fixed low pressure, and the bending will be serious after water cooling, which is very easy to damage the rotating facilities, and Unable to transport smoothly and need manual intervention, making the production efficiency low

[0006] Chinese patent CN2307006Y discloses a steel pipe external water spray device, which adopts a fixed low-pressure spray type of single-row cooling water pipes, and the cooling rate and uniformity are limited, especially for large-diameter steel pipes, it is difficult to obtain effective uniform cooling

[0007] Chinese patent CN201046978Y discloses a double-row outer shower pipe, which adopts a fixed low-pressure spray type of double-row cooling water pipes. The cooling rate is low. If the cooling water falls on the top of the steel pipe, it is easy to splash and the cooling efficiency is poor. , due to the difference in the height of the double-row spray pipes, the difference in water pressure and flow rate will lead to uneven cooling, and it is a mixed use of single and double rows, and it is even more uneven when only one row of spray pipes is used

[0008] Chinese patent CN101490286A discloses a steel pipe cooling method, which adopts a double-row laminar flow slit type. The slit laminar flow must form a stable curtain water flow, the length and flow range are limited, and the flow in the length direction cannot be adjusted, so it is not suitable for The quenching of quenched and tempered steel pipes is only applicable to steel pipes with a specific wall thickness / outer diameter ratio from its description

[0009] Chinese patent CN202705412U discloses a steel pipe quenching water spraying device, which adopts a low-pressure spraying type of double-row cooling water pipes, and sets an intermediate distribution water tank. Although it is equipped with a flow regulating valve, it mainly functions as an on-off valve from the description , and there is no pressure control device, it is difficult to maintain the flow balance of the entire length of the pipe body

[0010] Chinese patent CN204474716U discloses a quenching machine external spraying device, which adopts a low-pressure spraying type of double-row cooling water pipes, and sets a pressure-equalizing water tank to equalize the pressure. Although it can provide uniform pressure and flow for the entire length of the pipe body, once the device is manufactured After completion, the pressure is fixed and cannot be adjusted, and the full-length flow is also basically fixed

[0011] The above-mentioned off-line quenching devices for steel pipes mainly adopt the external spraying form of fixed low-pressure water spraying, the cooling rate is low and limited, and cannot be applied to quenching and tempering quenching by external spraying and internal spraying, nor can it effectively shorten the quenching time of steel pipes

At the same time, the non-adjustable configuration of double-row flow and pressure is difficult to meet the quenching process requirements of steel pipes of various specifications; due to the symmetrical arrangement of double-row nozzles, only a single row of nozzles can be used for small-diameter steel pipes to meet the cooling process, which is more likely to cause circumferential uneven cooling

[0012] The water quenching external cooling equipment currently used does not have a special water replenishment cooling design for the thickened end, which is difficult to meet the overall quenching requirements of thickened steel pipes

Although part of the cooling device uses multiple cooling spray boxes to cool the entire length of the steel pipe in sections, it is theoretically possible to increase the amount of cooling water at the thickened end, but once the set flow rate of the pipe body reaches or approaches the upper limit, the increased flow at the thickened end will decrease. It is very limited and cannot even be increased; and, even if the flow rate of the thickened end is increased, since the contact area between the cooling water and the steel pipe remains almost unchanged, the increased cooling rate is also very limited. For improving the performance and quality of the thickened end, Shortening the quenching time has little effect; at the same time, due to the difference in the length of the thickening end of various specifications of steel pipes, it will increase the design and calibration of external cooling equipment. It is also difficult to ensure the stability of the water system during the cooling process

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