研究不同回火工艺参数对在线淬火生产的3Cr2MnNiMo塑料模具钢板组织性能及硬度的影响.利用光学显微镜及硬度仪分析了试样的显微组织及硬度.结果表明:试样在线淬火后回火温度越高,硬度越低;600℃回火1h到2h时,硬度下降比较快,回火2h到8h时,硬度下降呈线性趋势.回火时间在2h内时,回火时间对硬度的影响程度要大;采用在线淬火方式冷却钢板硬度可以达到约为46～48 HRC时,应采用630℃回火4h可以得到28 ～ 36 HRC的回火硬度;采用在线淬火冷却钢板硬度达到约为43 ～46 HRC时,应采用610℃回火4h可以得到28～36 HRC的回火硬度.

A new online pre-hardening (OPH) equipment for quenching die steel has been developed by University of Science and Technology Beijing (USTB) and Dongbei Special Steel Group in Dalian Special Steel Co., LTD. OPH equipment consists of strong cooling water jet, medium cooling water jet, weak cooling water jet, air-water spray, and side water jet and has flexible cooling and control ability. Based on the equipment, online quenching process of AISI P20 (3Cr2Mo) die steel was performed by numerical simulation and production experiment. The result of temperature field by numerical simulation agrees well with experiment result, which can prove that numerical simulation can be a very good guidance for production experiment. Experimental tempering metallographic structure of the whole P20 plate is tempered troostite and the tempering hardness difference of P20 die steel can be controlled within 3 HRC in the whole plate under quenching process by numerical simulation. The prediction technology of numerical simulation can meet the different cooling rate control and make quenching process comply with preset quenching route to guarantee material microstructure and performance.

The thermal property parameters of 3Cr2NiMo plastic die steel were tested and the two-dimensional finite element model was established in the paper. The temperature fields of 3Cr2NiMo plastic die steel plate with the thickness of 130mm were calculated and analyzed under three quenching processes. The results showed that for all of the three processes the cooling rates could avoid the pearlite transformation zone when the temperature of the steel plate was more than 500 degrees C. When the temperature was less than 500 degrees C, the cooling rate of the third process was slower, and the temperature difference was effectively alleviated, which avoided large transformation stress appearance. For 3Cr2NiMo plastic die steel with the thickness of 130mm, the third process was the best process. In the paper, the hardness and the microstructures were tested after the third process and tempering. After tempering process, the structures were all tempered sorbite, and the tempering hardness difference in the whole steel plate was less than 3HRC, and there were no cracks. The study provided references for on-line pre-hardening process formulation and optimization of large plastic die steel.

The thermal parameters of 3Cr2Mo plastic die steel were tested. The temperature fields of 3Cr2Mo plastic die steel with the thickness 120mm were calculated and analyzed under two quenching processes. The results showed that for interrupted process the cooling velocity was faster when the temperature was more than 500°C, which was not in the transformation zone of bainite and martensite. And the fast cooling rate effectively avoided the pearlite appearance. When the temperature was less than 500°C, the cooling velocity under interrupted cooing process was slower, which avoided the big microstructure stress. So for the 3Cr2Mo plastic die steel with the thickness 120mm, the interrupted process was better. In the paper, the hardness was tested after interrupted cooling process and tempering. The tempering hardness difference was less than or equal to 3HRC. The study provided references for large plastic die steel on-line pre-hardening process formulation and optimization.

This article describes a production method of mould steel pre-hardening, and focus on the advantage of this method, The technical core of method is the variable frequency and variable amplitude pulse uniform high-precision temperature control, which achieved by using strong-medium-weak water cooling, gas-water cooling and gas mist cooling composite cooling control technology. Optimizing the cooling rate path is a good method of optimizing quenched organization and structure.

New on-line pre-hardening (OPH) equipment for quenching die steel has been developed by University of Science and Technology Beijing and Dongbei Special Steel Group in Dalian Special Steel Co., LTD. OPH consists of strong cooling water jet, medium cooling water jet, weak cooling water jet, air-water spray and side water jet and has flexible cooling and control ability. Based on the equipment, online quenching process of 718H die steel was performed by numerical simulation and production experiment. The result of temperature field by numerical simulation agrees well with experiment result, which can prove that numerical simulation can be a very good guidance for production experiment. Experimental tempering metallographic structure of the whole 718H plate is tempered troostite and sorbite and the tempering hardness difference of 718H die steel can be controlled within 2 HRC in the whole plate under on-line pre-hardening process by numerical simulation. The prediction technology of numerical simulation can meet the different cooling rate control and make quenching process comply with preset quenching route to guarantee material microstructure and performance.

To prove the effect of segmented roll height difference of tension measuring shapemeter with segmented rolls on measuring accuracy of the shapemeter as well as the qualitative and quantitative relation between them,experimental device is designed.It has the same mechanism and measuring theory with a type of shapemeter used in pratical production.The results of experiment show that,segmented roll height difference has great influence on shape measuring accuracy,there exists linear relation between them.The result of experiment accords with the 3D finite element analysis.The exploration of this device affords economical and convenient condition for the analysis of tension measuring shapemeter with segmented rolls.

Based on the current cooling method commonly used to cool outer surface by constant (i.e. low)pressure pipe jet and inner surface by high pressure axial jet, the numerical simulation by FEM software-FLUENT was performed to study temperature field of seamless steel pipe for quenching. The impact of the rotation speed is investigated on the steel pipe axial, circumferential and radial cooling uniformity. The numerical results reveal that, with the steel pipe speed increased, the rotation speed has a little influence on axial cooling uniformity and great impact on circumferential and radial cooling uniformity. Cooling uniformity of steel pipe is better under the condition of the rotation speed of no less than 60 rpm.

In the paper, the temperature distribution on the work roll surface of a 1750 hot strip mill is studied, and the variety rules of the thermal crown are analyzed. The result of test shows that the work roll thermal crown is significantly affected by cooling. The thermal crown obviously is improved after altering the distance between the cooling pipe and the work roll and changing the type of cooling water faucet. From this paper, it is known that different number of rolling coils cause different thermal crown of the work roll. The final change rule shows that the work roll thermal crown is the largest in Stand 1 and the smallest in Stand 6 in a rolling period.

Three-dimensional finite element flow field model of spraying pipe of roller-type quenching machine is built.The flow field with different structural parameters is computed.After grouping the nozzles,the spraying uniformity is analyzed under the conditions of different water inlet pipe diameter,different water inlet pipe distance,nozzle diameter and nozzle distance.And the spraying intensity absolute deviation and relative deviation are computed under different conditions.The effect of different structural parameters on cooling uniformity is obtained.The results provide theoretical basis for improving production quality and optimizing cooling device design.

Aiming at the temperature difference in the length direction along steel plate after air cooling field,the measures,gradually changing water quantity and adjusting roller velocity,were put forward to improve the cooling uniformity.The controlled cooling temperature field model of steel plate after normalizing is established.The two measures are computed through the established model.The temperature difference evidently decreases.For the best results,the cooling process parameters are optimized by ANSYS optimization model.The research results can provide theory foundation for accelerated controlled cooling system after normalizing to improve cooling uniformity and quality of steel plate.

This article took a tensiometer looper during hot rolling as the object of study.A three-dimensional finite element model was built for a tensiometer looper with roller-height-difference and a hot rolling strip.Considering roller-height-difference as a basic variable,the measurement error of flatness caused by roller-height-difference and its distribution rule under different situations were obtained by changing the arrangement of high and low rollers,the strip thickness,and the average tensile stress of the strip.

The transfer heat characteristics between air mist spray and high-temperature plate were researched by heat-flow coupling method.When the discrete-phase volume fraction was less than 10%～12%,the mixed convection heat transfer model was used.The effects of cooling parameters,such as air-water volume fraction,injection speed,gas-water velocity ratio,the distance of nozzle and plate,the temperature of the steel plate,on the heat transfer coefficient were researched.The results of this study provided important reference value for the material controlled cooling equipment development and the actual production.

Through analysis of shape measuring principle of tension measuring type shapemeter with segmented rolls,it is found that effect of width of segmented roller on shape detection precision is large.Shape curve can be divided into simple curve and complicated curve.Taking typical and practical shape curves as an example,effects of segmented roll width on shape detection precisions of strip with different widths were analyzed considering key character of strip′s shape curve,such as,monotonicity of curve,concavity and convexity of area where the extreme point is in,and steep or smooth degree of curve etc.Based on analysis results,shape detection errors and relative conclusions are obtained.

An Air Bearing Strip Flatness Detector (ABSFD), manufactured in China, was adapted to measure the strip flatness in cold rolling mills on-line. This paper presents how it works, static and dynamic characteristics, part edge strip cover roller and its transient response. It has been successfully serviced on line of 1400 aluminum foil cold rolling mill for six years, which the rolling speed is up to 9m/s. On the rolling of aluminum foils around 0.1mm, generally 97% of online shape reached 15 I, offline about 26 I.

This paper is based on the wear-resistant steel NM360 quenching experiments, simulates the steel plate quenching transient temperature field, and analyses the causes of quenching deformation. According to the experimental analysis, the martensitic phase transformation is the main reason of the wear-resistant steel quenching extremely easily deformation, therefore, how to control the time and stress of martensitic phase transformation of the plate surface is the key factor. Through experiments, we found a quenching process of controlling effectively quenching deformation, and it provides some practical experiences for acquiring the higher mechanical properties of this kind of wear-resisting steel.

Water Spray cooling is characterized by wide cooling range,large water flux adjustment and cooling uniformity.Water Spray cooling of the high temperature plat was numerically presented by using finite element coupling software-FLUENT.The effects of surface-to-nozzle distance,surface temperature of plate and jet flux or jet pressure on water spray cooling heat transfer coefficient were analyzed.The numerical results show that on condition that other parameters remain constant,heat transfer coefficient increases totally with decrease of jet space(200-500 mm),decreases totally with increase of surface temperature(1050-1200 K) and increases totally with increase of jet flux or jet pressure.This study can provide theoretical basis for the design of water spray cooling equipment and cooling process.

Real-time soft logic control system is first applied to automatic gauge control (AGC) system for copper cold strip reversing mill. IOWorks is used to develop the AGC system, which is based on Windows NT4.0 with real-time extension (RTX) operating system and standard IPC hardware. Adopting the IPC and soft logic can insure the requirements of real-time operations, while at the same time it can offer powerful processing and storage capacity, constitute the full digital AGC system and integrate the functions of basic automation and process automation. This system is accordant with the development trend of current industrial control and has many advantages such as openness, easy to use, integration, portability, low cost and so on. Practical application results show that the control period of automatic position control (APC) is 10 ms, and this system can achieve a high precision of 0.2±0.003 mm using the control mode of the mass flow AGC.

Numerical simulation was performed to study single-phase convective heat transfer at the impinging zone of non-immersed slot jet by a finite element method(FEM).In combination with the characteristic of rolled quenching machines,some influencing factors on heat transfer such as jet velocity,nozzle-to-impinging plate spacing(height),slot width,jet direction-to-plate angle,and the temperature of water(liquid) from the slot nozzle were analyzed and designed.The results show that,for quenching plates of 100 mm in thickness,the economic process parameters of slot jet are set as follows: jet velocity 40 to 45 m·s-1,nozzle-to-impinging plate spacing(height) about 20 mm,slot width about 2 mm,jet direction-to-plate angle about 45°,and the temperature of water(liquid) 10 to 35 ℃.

The speeds vary severely when the coal rake of stacker-reclaimer starts and commutates,and the strike shock is large and the buffer performance is not very ideal.The constuction requirements of a motion curve of hydraulic cylinder were analyzed,the mathematic model of hydraulic cylinder was built,the ideal motion curve equation was deduced by polynomials,the theoretical basis of this equation was given.This curve has the merit of minimum impulse.