阅读说明：本技术 百米热处理钢轨头尾温度控制方法 (Head and tail temperature control method for hectometer heat-treated steel rail ) 是由 张海旺 李钧正 韩志杰 杨正宗 武东东 郭朝军 王建锋 于 2020-04-26 设计创作，主要内容包括：本发明涉及一种百米热处理钢轨头尾温度控制方法；包括铸坯加热工序、万能机组轧制工序和热处理工序,所述铸坯加热工序,控制钢轨铸坯尾部加热温度、均热温度比铸坯头部加热温度、均热温度分别高出20～40℃；所述万能机组轧制工序,万能机组轧辊冷却水采用间歇性喷水,即在钢轨咬入时关掉冷却水,待钢轨咬入后再开启冷却水。本发明可将百米钢轨轧制完成后、在线热处理淬火冷却开始时,钢轨头部温度与钢轨尾部温度差控制在20℃以内,钢轨通长温度波动控制在30℃以内。(The invention relates to a head and tail temperature control method for a hectometer heat-treated steel rail; the method comprises a casting blank heating process, a universal unit rolling process and a heat treatment process, wherein in the casting blank heating process, the heating temperature and the soaking temperature of the tail part of a steel rail casting blank are controlled to be 20-40 ℃ higher than the heating temperature and the soaking temperature of the head part of the casting blank respectively; in the rolling process of the universal unit, the cooling water of the roller of the universal unit is sprayed intermittently, namely the cooling water is turned off when the steel rail is bitten, and the cooling water is turned on after the steel rail is bitten. The invention can control the temperature difference between the head temperature and the tail temperature of the steel rail within 20 ℃ and the full-length temperature fluctuation of the steel rail within 30 ℃ when the on-line heat treatment quenching cooling is started after the hundred-meter steel rail is rolled.)

1. The head and tail temperature control method for the hectometer heat-treated steel rail comprises a casting blank heating process, a universal unit rolling process and a heat treatment process, and is characterized in that: in the casting blank heating procedure, the heating temperature and the soaking temperature of the tail part of the steel rail casting blank are controlled to be 20-40 ℃ higher than the heating temperature and the soaking temperature of the head part of the casting blank respectively; in the rolling procedure of the universal unit, the cooling water of the roller of the universal unit is sprayed intermittently, the cooling water is turned off when the steel rail is bitten, and the cooling water is turned on after the steel rail is bitten.

2. The head-tail temperature control method of the hectometer heat-treated steel rail as claimed in claim 1, wherein: in the casting blank heating procedure, when the environmental temperature is 20-40 ℃, the heating temperature and the soaking temperature of the tail part of the steel rail casting blank are respectively 20-30 ℃ higher than the heating temperature and the soaking temperature of the head part of the casting blank; when the environmental temperature is higher than-10 ℃ and lower than 20 ℃, the heating temperature and the soaking temperature of the tail of the steel rail casting blank are respectively 31-40 ℃ higher than the heating temperature and the soaking temperature of the head of the casting blank.

3. The head-tail temperature control method of the hectometer heat-treated steel rail as claimed in claim 1, wherein: the universal mill set comprises a universal mill U1, an E mill and a universal mill U2, and the universal mill set comprises 3 rolling passes; and when the head of the 1 st rolling pass rolled piece reaches the inlet for hot inspection, the secondary descaling system is automatically started, when the tail of the rolled piece is separated from the U1 rolling mill, the secondary descaling system is automatically stopped, and the 2 nd rolling pass and the 3 rd rolling pass secondary descaling systems are not started.

4. The head-tail temperature control method of the hectometer heat-treated steel rail as claimed in claim 1 or 2, wherein: in the casting blank heating process, the temperature of a preheating section of a heating furnace is less than 850 ℃, and the temperature of a heating section is 1100-1180 ℃; when the environmental temperature is 20-40 ℃, the temperature of the head of the second-stage casting blank is 1230-1250 ℃, and the temperature of the head of the soaking section casting blank is 1210-1230 ℃; when the environmental temperature is higher than-10 ℃ and lower than 20 ℃, the temperature of the head of the casting blank at the heating second section is 1240-1260 ℃, and the temperature of the head of the casting blank at the soaking section is 1220-1240 ℃.

5. The head-tail temperature control method of the hectometer heat-treated steel rail as claimed in claim 1, wherein: the heat treatment process is an accelerated cooling treatment process for the rolled steel rail, and the inlet temperature of the head and the tail of the steel rail in a heat treatment cooling section is 650-800 ℃.

6. The head-tail temperature control method of the hectometer heat-treated steel rail as claimed in claim 1, wherein: the steel rail specification is 50kg/m, 60kg/m, 75kg/m, 60N, 75N, 54E1, 60E1 and 60E2, and the rolling length of the steel rail is 100-110 m.

Technical Field

The invention relates to a method for controlling the temperature of a steel rail, in particular to a method for controlling the head and tail temperature of a hectometer heat-treated steel rail.

Background

The production process flow of the hectometer online heat treatment steel rail comprises the following steps: heating a steel rail casting blank, descaling with high-pressure water, rolling with a cogging mill, rolling with a universal unit, thermal printing, online thermal treatment, cooling with a cooling bed, straightening, flaw detection, online inspection, saw cutting and collection. After being rolled into steel rails for multiple times by a multi-frame rolling mill, the steel rail casting blanks are transported to on-line quenching equipment for heat treatment by a roller way.

In actual production, the cooling conditions of the head and the tail of the hectometer steel rail in the rolling process are different from the middle of the steel rail, the cooling time of the head and the tail of the steel rail in a heat treatment cooling section is different, the temperature difference of the head, the tail and the middle of the steel rail is large when the heat treatment starts to cool, the temperature of the tail of the steel rail is generally lower than the temperature of the head by 50-80 ℃, and the temperature of the head is lower than the temperature of the middle of the steel rail by 20.

The heat treatment temperature is a key parameter of a heat treatment process, the temperature uniformity of the steel rail before the steel rail is cooled is an important factor influencing the structure uniformity of the steel rail after the steel rail is cooled, the hardness difference of a tread of the steel rail can reach 10-25 HB after the steel rail with uneven temperature is cooled, the steel rail with uneven hardness is prone to wave grinding too early when in use, and the service life of the steel rail is shortened.

In order to make the structure performance of the on-line heat treatment steel rail uniform and the hardness fluctuation range small, a heating device is usually arranged in front of a quenching cooling unit to heat the steel rail for temperature compensation so as to keep the temperature uniformity of the steel rail; the process arrangement not only increases the equipment investment, but also increases the production cost due to the heat compensation of the steel rail, and simultaneously reduces the production efficiency of the online heat treatment of the steel rail.

Disclosure of Invention

The invention aims to provide a method for controlling the head and tail temperature of a hectometer heat-treated steel rail, which can reduce the head and tail temperature difference when the hectometer steel rail starts to be cooled during heat treatment.

In order to solve the problems, the invention adopts the technical scheme that:

the method for controlling the head and tail temperature of the hectometer heat-treated steel rail comprises a casting blank heating process, a universal unit rolling process and a heat treatment process, wherein in the casting blank heating process, the tail heating temperature and the soaking temperature of the steel rail casting blank are controlled to be 20-40 ℃ higher than the head heating temperature and the soaking temperature of the steel rail casting blank respectively; in the rolling process of the universal unit, the cooling water of the roller of the universal unit is sprayed intermittently, namely the cooling water is turned off when the steel rail is bitten, and the cooling water is turned on after the steel rail is bitten.

In the casting blank heating process, when the environmental temperature is 20-40 ℃, the heating temperature and the soaking temperature of the tail of the steel rail casting blank are respectively 20-30 ℃ higher than the heating temperature and the soaking temperature of the head of the casting blank; when the environmental temperature is higher than-10 ℃ and lower than 20 ℃, the heating temperature and the soaking temperature of the tail of the steel rail casting blank are respectively 31-40 ℃ higher than the heating temperature and the soaking temperature of the head of the casting blank.

According to the method for controlling the head and tail temperature of the hectometer heat-treated steel rail, the universal set comprises a universal rolling mill U1, an E rolling mill and a universal rolling mill U2, and the universal rolling set comprises 3 rolling passes; and when the head of the 1 st rolling pass rolled piece reaches the inlet for hot inspection, the secondary descaling system is automatically started, when the tail of the rolled piece is separated from the U1 rolling mill, the secondary descaling system is automatically stopped, and the 2 nd rolling pass and the 3 rd rolling pass secondary descaling systems are not started.

According to the method for controlling the head and tail temperature of the hectometer heat-treated steel rail, in the casting blank heating process, the temperature of the preheating section of a heating furnace is less than 850 ℃, and the temperature of the heating section is 1100-1180 ℃; when the environmental temperature is 20-40 ℃, the temperature of the head of the second-stage casting blank is 1230-1250 ℃, and the temperature of the head of the soaking section casting blank is 1210-1230 ℃; when the environmental temperature is higher than-10 ℃ and lower than 20 ℃, the temperature of the head of the casting blank at the heating second section is 1240-1260 ℃, and the temperature of the head of the casting blank at the soaking section is 1220-1240 ℃.

In the method for controlling the head and tail temperature of the hectometer heat-treated steel rail, the heat treatment process refers to an accelerated cooling treatment process for the rolled steel rail, and the inlet temperature of the head and tail of the steel rail in a heat treatment cooling section is 650-800 ℃.

According to the head and tail temperature control method for the hectometer heat-treated steel rail, the steel rail specification is 50kg/m, 60kg/m, 75kg/m, 60N, 75N, 54E1, 60E1 and 60E2, and the rolling length of the steel rail is 100-110 m.

The imported heat detection means a device which can automatically sense the position of the steel rail in front of the rolling mill and transmit a steel rail position signal to a rolling mill control system, and the rolling mill control system sends a related instruction according to the position of the steel rail; the secondary descaling system is a descaling water system in front of the universal mill U1, and scale produced or remained in the rolling process is removed.

The universal rolling mill group consists of two universal rolling mills with vertical rolls and a two-roll edging mill, wherein the universal rolling mills are respectively called a U1 rolling mill and a U2 rolling mill, the edging mill is called an E rolling mill, and the universal rolling mills and the edging mill are arranged according to the sequence of a steel rail entering the rolling mill: u1 Rolling Mill-edger E-U2 Rolling Mill; the steel rail is continuously and reversibly rolled between three rolling mills of the universal machine set, namely, after the steel rail reaches the universal machine set, the head of the steel rail enters a U1 rolling mill and is sequentially rolled by U1 and E, U2 rolling mills, which is called as the 1 st rolling pass; after the rolling in the 1 st rolling process is finished, the tail part of the steel rail enters a U2 rolling mill, and the steel rail is rolled by U2 and E, U1 rolling mills in sequence, which is called as a 2 nd rolling process; after the 2 nd rolling process is finished, the head of the steel rail enters a U1 rolling mill and then passes through U1 and E, U2 rolling mills in sequence, and the process is called as a 3 rd rolling process.

At present, the steel rail is rolled by a cogging mill and then reaches a universal mill train, cooling water of each stand mill of the universal mill train is started, continuous spraying is carried out to cool a roller, and the cooling water is closed only after the steel rail leaves the universal mill train. In order to prevent the 'slipping', namely the steel rail can not normally enter a rolling mill, a lower rolling speed is adopted, and the rolling speed is generally 1-1.5 m/s; the high rolling speed is adopted after the steel rail is bitten, and the rolling speed is generally 3.5-6 m/s. When the steel rail is bitten, the rolling time at the head part of the 1 st rolling process and the 3 rd rolling process is longer due to lower rolling speed, the rolling time at the tail part of the steel rail of the 2 nd rolling process is longer, and a large amount of roller cooling water and descaling water are poured onto the steel rail, so that the temperature drop of the head part and the tail part of the steel rail is large.

The invention aims at the large temperature difference between the head and the tail of a hectometer heat-treated steel rail before quenching, the head and the tail of the steel rail are lower than the temperature of other parts of the steel rail, the temperature of the steel rail in the cooling process from the furnace discharge of a heating furnace to the quenching heat treatment is analyzed, the spraying time of the head and the tail of the steel rail by secondary descaling water and roller cooling water is far longer than that of the other parts of the steel rail by the roller cooling water when the steel rail is rolled by a universal unit, and therefore, the temperature drop of the head and the tail of the steel rail is larger than that of the other parts of the steel rail when the steel rail.

Aiming at the problem that the cooling temperature of the steel rail at the head and the tail of the universal unit is higher than that of other parts, the control process of roller cooling water and secondary descaling water is optimized, the roller cooling water of the universal unit is changed from continuous spraying to intermittent spraying, namely the cooling water is turned off when the steel rail is bitten, and the cooling water is turned on after the steel rail is bitten (the head of the steel rail is output from a U2 rolling mill in the 1 st rolling process and the head of the steel rail is output from a U1 rolling mill in the 3 rd rolling process, and the tail of the steel rail is output; the secondary descaling system is automatically started when the head of the universal 1 st rolling pass rolled piece reaches the inlet thermal inspection, and is automatically stopped when the tail of the universal 1 st rolling pass rolled piece is separated from the U1 rolling mill; the 2 nd and 3 rd rolling process secondary descaling system is not started.

Adopt above-mentioned scheme beneficial effect to be:

according to the invention, after the hectometer steel rail is rolled, when the on-line heat treatment quenching cooling is started, the temperature difference between the head of the steel rail and the tail of the steel rail is controlled within 20 ℃, and the full-length temperature fluctuation of the steel rail is controlled within 30 ℃, so that a guarantee is provided for obtaining uniform structure performance of the hectometer steel rail after quenching; the hardness difference of the steel rail tread is controlled within 10HB, so that the condition that the corrugation is too early in use due to uneven hardness of the steel rail is avoided (the corrugation is damage to the steel rail and refers to the phenomenon that the periodic irregularity similar to the corrugation appears on the longitudinal surface of the steel rail, the corrugation can increase noise in train operation and simultaneously generates potential safety hazards), and the service life of the steel rail is prolonged.

Detailed Description