阅读说明：本技术 轧辊辊型的磨削控制方法 (Grinding control method for roller profile ) 是由 杨宴宾 张国民 吴真权 幸利军 于 2019-03-19 设计创作，主要内容包括：本发明公开了一种轧辊辊型的磨削控制方法,包括如下步骤：步骤1：通过在线计算机模型读入下机时刻的轧辊的温度场及物性参数；步骤2：根据离线轧辊的冷却边界条件,计算温度场的动态变化；步骤3：确定轧辊磨削辊型的温度补偿量；步骤4：确定轧辊的磨削辊型,设定目标初始辊型,计算带温磨削时的温度补偿量,计算修正后的磨削辊型；步骤5：在数控轧辊磨床中设定轧辊磨削的辊型参数,并对轧辊进行磨削。本发明能通过磨削时轧辊的温度场和热膨胀情况修正磨削目标辊型,从而保证轧辊辊型的正确磨削。(The invention discloses a grinding control method of a roller profile, which comprises the following steps: step 1: reading in the temperature field and physical property parameters of the roller at the time of starting-up through an online computer model; step 2: calculating the dynamic change of the temperature field according to the cooling boundary condition of the off-line roller; and step 3: determining the temperature compensation quantity of a grinding roller shape of the roller; and 4, step 4: determining a grinding roller shape of the roller, setting a target initial roller shape, calculating a temperature compensation amount during grinding with temperature, and calculating a corrected grinding roller shape; and 5: setting roll shape parameters of roll grinding in the numerical control roll grinder, and grinding the roll. The invention can correct and grind the target roll profile through the temperature field and thermal expansion condition of the roll during grinding, thereby ensuring the correct grinding of the roll profile of the roll.)

1. A grinding control method of a roller profile is characterized in that: the method comprises the following steps:

step 1: reading in the temperature field and physical property parameters of the roller at the time of starting-up through an online computer model;

step 2: calculating the dynamic change of the temperature field according to the cooling boundary condition of the off-line roller;

and step 3: determining the temperature compensation quantity of a grinding roller shape of the roller;

step 3.1: calculating the thermal expansion amount of the roller, wherein the thermal expansion amount at any point z on the surface of the roller body of the roller is as follows:

wherein ν is Poisson's ratio, β is coefficient of thermal expansion, R is roll radius, T₀Is the initial temperature, T is the temperature, r is the radial coordinate of the roller, and z is the axial coordinate of the roller;

step 3.2: calculating the relative expansion of the roller, wherein the relative expansion of any point z on the surface of the roller body of the roller is as follows:

△u_t(z)＝u_t(z)-u_t(e) (8)

wherein u is_t(e) The thermal expansion amount at a representative point e of the edge of the roll;

step 3.3: fitting the relative expansion amount, and calculating the roll profile grinding compensation amount at any point z on the surface of the roll body:

△u_t(z)＝a₀+a₂z²+a₄z⁴(9)

wherein, a₀、a₂And a₄Is a fitting coefficient;

and 4, step 4: determining grinding roll shape of the roll, and setting a target initial roll shape to be u₀(z) calculating a temperature compensation amount during warm grinding, and calculating a corrected grinding roll profile:

u(z)＝u₀(z)+△u_t(z) (10)；

and 5: setting roll shape parameters of roll grinding in the numerical control roll grinder, and grinding the roll.

2. The grinding control method of a roll profile according to claim 1, wherein: in the step 1, the physical parameters of the roller comprise density, specific heat and thermal conductivity.

3. The grinding control method of a roll profile according to claim 1, wherein: in step 2, the calculation formula of the dynamic change of the temperature field is as follows:

wherein T is temperature, T is time, ρ is density of the roll material, c is specific heat of the roll material, λ is thermal conductivity of the roll material, and r and z are radial and axial coordinates of the roll, respectively.

4. The grinding control method of a roll profile according to claim 1, wherein: in the step 2, the roller cooling process comprises air cooling before forced cooling, forced water spraying cooling and air cooling after forced cooling.

5. The grinding control method of a roll shape according to claim 1 or 4, characterized in that: the cooling boundary conditions in the cooling process of the roller comprise a left-right symmetric boundary, an up-down symmetric boundary, a surface boundary of a roller body and a roller diameter, a boundary of a contact part of the roller and a bearing and a boundary of an end part of the roller.

6. The grinding control method of a roll shape according to claim 5, characterized in that: the calculation formula of the roll bilateral symmetry boundary is as follows:

wherein T is temperature, lambda is the thermal conductivity of the roll material, and z is the roll axial coordinate.

7. The grinding control method of a roll shape according to claim 5, characterized in that: the calculation formula of the upper and lower symmetrical boundaries of the roller is as follows:

wherein T is temperature, lambda is the thermal conductivity of the roll material, and r is the radial coordinate of the roll.

8. The grinding control method of a roll shape according to claim 5, characterized in that: the calculation formula of the surface boundary of the roller body and the roller diameter is as follows:

where T is the temperature, λ is the thermal conductivity of the roll material, r is the roll radial coordinate, α_AIs the heat transfer coefficient between the roll and the air, T_AIs the air temperature.

9. The grinding control method of a roll shape according to claim 5, characterized in that: the calculation formula of the boundary of the contact part of the roller and the bearing is as follows:

where T is the temperature, λ is the thermal conductivity of the roll material, r is the roll radial coordinate, α_BIs the heat transfer coefficient between the roll and the bearing, T_BIs the bearing temperature.

10. The grinding control method of a roll shape according to claim 5, characterized in that: the calculation formula of the end boundary of the roller is as follows:

where T is the temperature, λ is the thermal conductivity of the roll material, z is the roll axial coordinate, α_AIs the heat transfer coefficient between the roll and the air, T_AIs the air temperature.

Technical Field

The invention relates to a production method of hot-rolled strip steel, in particular to a grinding control method of a roller profile.

Background

The roll is an important component of a hot strip rolling mill and comprises a roll body 1, a roll shoulder 2 and a roll neck 3, as shown in figure 1. During rolling, the roll surfaces wear. In order to ensure the shape and surface quality of the strip steel product, after rolling for a certain kilometer, the roller needs to be dismounted and ground again.

In order to ensure the accuracy of the initial roll shape, the temperature of the ground roll needs to be cooled to room temperature. However, in order to increase the roll turnover rate, regrinding may be performed without cooling to room temperature. At the moment, because of thermal expansion, the grinding roller shape has deviation, which causes inaccurate roll gap shape setting in the use of a machine, thereby influencing the shape quality control of the hot rolled strip steel plate and causing wave-shaped defects and out-of-tolerance of convexity.

Japanese patent application JP11005106A discloses a roll grinding method involving a grinding roll profile compensation method with uneven temperature distribution along the length of the roll. In the invention, the surface temperature of the roller is measured by a sensor and fed back to a roller control system in real time so as to compensate the grinding roller shape by considering the temperature influence. However, the thermal expansion of the roll is determined by the overall temperature distribution of the roll, and the method can only measure the surface temperature of the roll, and the internal temperature distribution cannot be accurately known, so that the grinding roll shape cannot be accurately compensated for the influence of the temperature.

Disclosure of Invention

The invention aims to provide a grinding control method of a roller profile, which can correct a grinding target roller profile through a temperature field and a thermal expansion condition of a roller during grinding so as to ensure the accurate grinding of the roller profile of the roller.

The invention is realized by the following steps:

a grinding control method of a roller profile comprises the following steps:

step 1: reading in the temperature field and physical property parameters of the roller at the time of starting-up through an online computer model;

step 2: calculating the dynamic change of the temperature field according to the cooling boundary condition of the off-line roller;

and step 3: determining the temperature compensation quantity of a grinding roller shape of the roller;

step 3.1: calculating the thermal expansion amount of the roller, wherein the thermal expansion amount at any point z on the surface of the roller body of the roller is as follows:

wherein ν is Poisson's ratio, β is coefficient of thermal expansion, R is roll radius, T₀Is the initial temperature, T is the temperature, r is the radial coordinate of the roller, and z is the axial coordinate of the roller;

step 3.2: calculating the relative expansion of the roller, wherein the relative expansion of any point z on the surface of the roller body of the roller is as follows:

△u_t(z)＝u_t(z)-u_t(e) (8)

wherein u is_t(e) The thermal expansion amount at a representative point e of the edge of the roll;

step 3.3: fitting the relative expansion amount, and calculating the roll profile grinding compensation amount at any point z on the surface of the roll body:

△u_t(z)＝a₀+a₂z²+a₄z⁴(9)

wherein, a₀、a₂And a₄Is a fitting coefficient;

and 4, step 4: determining grinding roll shape of the roll, and setting a target initial roll shape to be u₀(z) calculating a temperature compensation amount during warm grinding, and calculating a corrected grinding roll profile:

u(z)＝u₀(z)+△u_t(z) (10)；

and 5: setting roll shape parameters of roll grinding in the numerical control roll grinder, and grinding the roll.

In the step 1, the physical parameters of the roller comprise density, specific heat and thermal conductivity.

In step 2, the calculation formula of the dynamic change of the temperature field is as follows:

wherein T is temperature, T is time, ρ is density of the roll material, c is specific heat of the roll material, λ is thermal conductivity of the roll material, and r and z are radial and axial coordinates of the roll, respectively.

In the step 2, the roller cooling process comprises air cooling before forced cooling, forced water spraying cooling and air cooling after forced cooling.

The cooling boundary conditions in the cooling process of the roller comprise a left-right symmetric boundary, an up-down symmetric boundary, a surface boundary of a roller body and a roller diameter, a boundary of a contact part of the roller and a bearing and a boundary of an end part of the roller.

The calculation formula of the roll bilateral symmetry boundary is as follows:

wherein T is temperature, lambda is the thermal conductivity of the roll material, and z is the roll axial coordinate.

The calculation formula of the upper and lower symmetrical boundaries of the roller is as follows:

wherein T is temperature, lambda is the thermal conductivity of the roll material, and r is the radial coordinate of the roll.

The calculation formula of the surface boundary of the roller body and the roller diameter is as follows:

where T is the temperature, λ is the thermal conductivity of the roll material, r is the roll radial coordinate, α_AIs the heat transfer coefficient between the roll and the air, T_AIs the air temperature.

The calculation formula of the boundary of the contact part of the roller and the bearing is as follows:

where T is the temperature, λ is the thermal conductivity of the roll material, r is the roll radial coordinate, α_BIs the heat transfer coefficient between the roll and the bearing, T_BIs the bearing temperature.

The calculation formula of the end boundary of the roller is as follows:

where T is the temperature, λ is the thermal conductivity of the roll material, z is the roll axial coordinate, α_AIs the heat transfer coefficient between the roll and the air, T_AIs the air temperature.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention can correct and grind the target roll profile through the temperature field and thermal expansion condition of the roll during grinding, reduce the set deviation of the on-machine production, and realize the setting of the roll grinding profile, thereby ensuring the correct grinding of the roll profile of the roll and improving the set precision and the quality of the hot rolled profile.

2. The invention is suitable for regrinding after the roller is off the mill in the production of hot rolled strips and slowly cooled in the air within 14 hours, and is also suitable for regrinding after the roller is off the mill and cooled by water spraying for 20-120 minutes, and has wide popularization and application prospects.

Drawings

FIG. 1 is a front view of a prior art roll;

FIG. 2 is a flow chart of a method of controlling grinding of a roll profile of the roll of the present invention;

FIG. 3 is a schematic view of a finite difference grid of rolls for the grinding control method of the roll profile of the rolls of the present invention;

fig. 4 is a graph showing changes in the relative thermal expansion of the roll in example 1 of the grinding control method for a roll profile of a roll according to the present invention.

Detailed Description

The invention is further described with reference to the following figures and specific examples.

Referring to fig. 2, a method for controlling grinding of a roll profile of a roll includes the following steps:

step 1: the temperature field of the roll and each physical property parameter at the time of the start-up are read by an online computer model, and preferably, the physical property parameters of the roll include density, specific heat, thermal conductivity, and the like.

Step 2: after the roll is removed, the roll is sometimes placed in a roll workshop for natural air cooling, and sometimes water spray forced cooling is required. Assuming that the roll temperature field is symmetrically distributed relative to the roll axis and the middle of the roll body, and neglecting heat transfer along the circumferential direction, the dynamic change of the temperature field is calculated according to the cooling boundary condition of the off-line roll, and the calculation formula is as follows:

wherein T is temperature, T is time, ρ is density of the roll material, c is specific heat of the roll material, λ is thermal conductivity of the roll material, and r and z are radial and axial coordinates of the roll, respectively.

Referring to fig. 3, a difference grid is established by taking one quarter of a section passing through the axis of the roll, and a finite difference method is adopted to solve the differential equation (1).

The roller cooling process comprises air cooling before forced cooling, forced water spraying cooling and air cooling after forced cooling.

The cooling boundary conditions in the cooling process of the roller comprise a left-right symmetric boundary, an up-down symmetric boundary, a roller body, a surface boundary of the roller diameter, a boundary of a contact part of the roller and a bearing and a boundary of an end part of the roller.

Wherein, the calculation formula of the bilateral symmetry boundary of the roller is as follows:

wherein T is temperature, lambda is the thermal conductivity of the roll material, and z is the roll axial coordinate.

The calculation formula of the upper and lower symmetrical boundaries of the roller is as follows:

wherein T is temperature, lambda is the thermal conductivity of the roll material, and r is the radial coordinate of the roll.

The calculation formula of the surface boundary of the roller body and the roller diameter is as follows:

where T is the temperature, λ is the thermal conductivity of the roll material, r is the roll radial coordinate, α_AIs the heat transfer coefficient between the roll and the air, T_AIs the air temperature.

The calculation formula of the boundary of the contact part of the roller and the bearing is as follows:

where T is the temperature, λ is the thermal conductivity of the roll material, r is the roll radial coordinate, α_BIs the heat transfer coefficient between the roll and the bearing, T_BIs the bearing temperature.

The calculation formula of the end boundary of the roller is as follows:

where T is the temperature, λ is the thermal conductivity of the roll material, z is the roll axial coordinate, α_AIs the heat transfer coefficient between the roll and the air, T_AIs the air temperature.

And step 3: and determining the temperature compensation quantity of the grinding roll profile of the roll.

Step 3.1: calculating the thermal expansion amount of the roller, wherein the thermal expansion amount at any point z on the surface of the roller body of the roller is as follows:

wherein ν is Poisson's ratio, β is coefficient of thermal expansion, R is roll radius, T₀The initial temperature, T the temperature and r the radial coordinates of the roll.

Step 3.2: calculating the relative expansion of the roller, wherein the relative expansion of any point z on the surface of the roller body of the roller is as follows:

△u_t(z)＝u_t(z)-u_t(e) (8)

wherein u is_t(e) The amount of thermal expansion at the roll edge is represented by the amount of thermal expansion at point e, which is typically 25 or 40mm from the edge.

Step 3.3: fitting the relative expansion amount, and calculating the roll profile grinding compensation amount at any point z on the surface of the roll body:

△u_t(z)＝a₀+a₂z²+a₄z⁴(9)

wherein, a₀、a₂And a₄Are fitting coefficients.

And 4, step 4: determining grinding roll shape of the roll, and setting a target initial roll shape to be u₀(z) calculating a temperature compensation amount during warm grinding, and calculating a corrected grinding roll profile:

u(z)＝u₀(z)+△u_t(z) (10)

in one rolling period, the same set of rollers is used to meet the requirements of all product shape control. As in the hot strip rolling production, the initial roll profile u is usually formed due to the large thermal expansion and crown caused by the heated roll₀(z) grinding to a parabolic or sinusoidal profile with a negative convexity.

And 5: setting roll shape parameters of roll grinding in the numerical control roll grinder, and grinding the roll.