JPH03134121A - Device for controlling temperature of material to be heated in continuous heating furnace - Google Patents

Abstract

PURPOSE:To exactly heating a material to be heated so that the temp of the material to be heated becomes the aimed temp. without causing lowering of the productivity and meandering by adjusting retention time of the material to be heated in a furnace by changing strip passing distance in the heating furnace. CONSTITUTION:The time when a welded point is entered into the heating furnace is predicted with a main control unit 8 from the actual strip. passing speed detected with a strip passing speed meter 4 and the position of the welded point detected with a welded point detector 3. The optimum transition track for heating furnace temp. is decided from the predicted time and steel strip specification set to the steel strip specification setting device 11 to execute control of the furnace temp. with a furnace temp. control unit 12. The optimum track of the strip passing distance in the furnace is decided from the retention time in the furnace obtd. by counting back and the strip passing speed of the steel strip specification. Based on this, setting position of upper roll line 61 in a strand looper 60 is controlled with a looper position control unit 13. By this method, the range out of the aimed value for steel strip temp. at outlet in the heating furnace can be narrowed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a method for welding various plate-shaped materials to be heated, such as various steel plates having different plate thicknesses, plate widths, materials, or target temperatures at the outlet of a heating furnace. What is the temperature of the steel plate when it is continuously passed through a heating furnace? 11 device.

[Prior art]

Cold-rolled steel sheets are subjected to heat treatment that combines heating, soaking, cooling, etc. in order to impart the required properties, and this heat treatment is carried out continuously and at high speed to improve productivity. It will be held on.

In recent years, steel plates inserted into continuous annealing furnaces have become welded coils of different plate thicknesses, plate widths, and materials due to the demand for a wide variety of products and small lofts. For this reason, it is necessary to frequently change the furnace temperature setting value in each heat treatment furnace.

By the way, as a heating method in a heating furnace, an indirect heating method using a radiant tube, etc. is widely adopted from the viewpoint of preventing oxidation of the steel plate. The drawback is that the followability of temperature values is extremely low.

For example, in the device proposed in Japanese Patent Application Laid-open No. 57-35640, when controlling the steel plate temperature before and after the welding point of the steel plate enters the heating furnace, the amount and timing of change in the furnace temperature setting value can be controlled by controlling the amount and timing of the change. The furnace temperature setting value is calculated in advance according to the above conditions, and the furnace temperature setting value is changed based on the calculation result.

FIG. 3 is a diagram showing an example of controlling the copper plate temperature by the above-mentioned apparatus, and shows control of a welded portion of steel plates having the same plate width, material, and target temperature, but differing only in plate thickness. First, the set value of the furnace temperature is changed as shown by the solid line according to the plate thickness, and the actual value is changed as shown by the broken line.

Then, the steel plate temperature deviates from the hatched region with respect to the target temperature before and after the welding point due to poor followability of the actual furnace temperature value. This means that the larger the amount of change in the furnace temperature set value is, the longer the temperature will deviate from the target temperature. If the steel plate temperature deviates from the target temperature in this way, the steel plate may be under-baked or overbaked, resulting in a decrease in the yield of the product.

Therefore, Japanese Patent Laid-Open No. 190026/1983 proposed a device that eliminates this problem and also uses control to change the speed at which the steel sheet passes. This is because the temperature of the steel plate at the outlet of the heating furnace is determined by the temperature of the steel plate when it is inserted into the heating furnace, the furnace temperature, and the time the steel plate stays in the heating furnace. This is to adjust the stay time.

[Problem to be solved by the invention]

However, in the above-mentioned conventional apparatus, when the residence time of the steel plate in the heating furnace is increased, the threading speed is reduced, but there is a problem in that the productivity is also reduced accordingly. Furthermore, since changing the sheet threading speed causes meandering of the steel sheet, there is also the problem that certain restrictions are imposed on the operation.

The present invention has been made in view of such circumstances, and provides a device that can change the threading distance in the heating furnace to control the residence time of the material to be heated in the heating furnace without changing the threading speed. By doing this, the area where the temperature of the material to be heated at the outlet of the heating furnace deviates from the target temperature before and after the welding point is reduced as much as possible, and even in a steady state other than the welding point, the temperature of the material to be heated is The object of the present invention is to provide a temperature control device for a heated material in a continuous heating furnace that can maintain the temperature at a target temperature.

[Means to solve the problem]

The temperature control device for a material to be heated in a continuous heating furnace according to the present invention continuously passes various plate-shaped materials to be heated through the heating furnace to heat the material, and controls the temperature of the material at the outlet of the heating furnace. A temperature control device for a heated material that controls the temperature of each heating material to a target temperature, which is provided in the heating furnace and extends or shortens the mail order distance of the heated material; A threading distance determining means for determining a threading distance of the material to be heated in the heating furnace, and a means for setting the threading distance determined by the threading distance determining means in the threading distance changing section. It is characterized by

[Effect]

A sheet passing distance changing section is provided in the heating furnace, and the sheet passing distance is set by the sheet passing distance changing section, which is determined based on the target temperature of the material to be heated at the outlet of the heating furnace. Then, the residence time of the material to be heated in the heating furnace is changed according to the passing distance, so that the material to be heated is heated just enough to reach the target temperature.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof. FIG. 1 is a schematic diagram showing the configuration of a temperature control device for a heated material in a continuous heating furnace according to the present invention. A strip 1 in which a plurality of coils having different thicknesses, widths, and materials are welded is held between a pair of drive rolls 2 and passed in the direction of the arrow.

The roll driving device 10 adjusts the driving speed of the roll pair 2 to achieve the sheet passing speed set in the steel plate specification setting device 11 according to the operating conditions. In addition to the threading speed, the steel plate specification setting device 11 is set with a preheating target temperature of the strip 1 and a target temperature at the outlet of the heating furnace.

%IX On the downstream side of the IJI roll pair 2 in the strip passing direction, a welding point detector 31, a strip passing speed meter 4, and a copper plate thermometer 5 for detecting the inlet temperature of the heating furnace 6 are installed in order. This is applied to the main controller 8 which is the sheet passing distance determining means. The main controller 8 also includes the steel plate specification setting device 1.
Data for each setting of 1 is sent.

The temperature inside the heating furnace 6 is adjusted by a furnace temperature control device 12, and a control signal from the main control device 8 is given to the furnace temperature control device 12. Further, a strand looper 60 is installed in the heating furnace 6 as the threading distance changing section for changing the threading distance of the strip 1. The strand looper 60 includes an upper roll row 61 and a lower roll row 62, and the lower roll row 62 of the upper roll row 61
By being configured to be able to change the distance between the strips 1 and 1, it is possible to change the distance that the strip 1 passes through the heating furnace 6, that is, the time that the strip 1 stays in the furnace. Upper roll row 6
The movement of the heating furnace 6 is controlled by a looper position control device 13, and a control signal from a main control device 8 is given to the looper position control device 13. Strand looper 6
Set to 0. Further, the moving position of the upper roll row 61 is detected by a looper position detector 7, and this detection signal is inputted to the main controller 8. Such a control technique for the strand looper 60 is already established today.

A steel plate thermometer 9 is installed at the outlet of the heating furnace 6, and a detection signal of the steel plate temperature is input to the main controller 8.

Now, in the apparatus of the present invention configured as described above, first, the main controller 8 starts welding based on the current threading speed detected by the threading speed meter 4 and the welding point detected by the welding point detector 3. Predict the heating furnace insertion time of a point. Then, based on the predicted heating furnace insertion time and the steel plate specifications set in the steel plate specification setting device 11, an optimal transition trajectory of the heating furnace temperature is determined using a known steel plate temperature control model, and the furnace temperature is controlled by the furnace temperature control device 12. Controls temperature.

Here, a deviation occurs in a transient state between the steel plate temperature transition trajectory derived by the steel plate temperature control model and the target value, but if the same model is used, the deviation becomes zero w4
It is mathematically possible to back-calculate the temporary residence time in the furnace.

Therefore, the optimum trajectory and path for passing the steel plate through the furnace is determined from the back-calculated residence time in the furnace and the threading speed according to the steel plate specifications. Then, the set position of the upper roll row 61 of the strand looper 60 is controlled by the looper position control device 13 based on the optimum trajectory of the sheet passing distance in the furnace. As a result, the range in which the temperature of the steel plate at the outlet of the heating furnace deviates from the target value can be significantly reduced compared to conventional devices.

Furthermore, even when the steel plate temperature deviates from the target value due to disturbance in a steady state, the set position of the upper roll row 61 of the strand looper 60 is controlled by feeding back the detected value of the steel plate thermometer 9 at the outlet of the heating furnace. This allows the i-plate temperature to be maintained at the target value.

FIG. 2 is a graph showing the results of temperature control of a strip obtained by welding steel plates of different thicknesses (target temperature is the same) using the apparatus of the present invention. ms in the figure shows the plate thickness and welding points.

The same figure (bl shows the predicted transition trajectory of the set value (solid line) and actual value (broken line) of the temperature inside the heating furnace determined using a known temperature control model. Under the furnace temperature control shown in this figure, the strip The predicted transition trajectory of the steel plate temperature when heating is shown in Figure 2 (
This is the broken line in C). No matter what conventional temperature control model is used, it is technically impossible to reduce the deviation of the steel sheet temperature from the target value to zero.

Therefore, in the device of the present invention, in addition to the above-mentioned furnace temperature control,
The strand looper 60 controls the distance through which the sheet passes through the heating furnace, as shown in FIG. In other words, if the steel plate temperature is expected to deviate upwards as shown by the broken line in Figure 2 (C), the strip passing distance in the heating furnace should be adjusted under normal operation so that the deviation from the target temperature is zero. On the other hand, when the steel plate temperature deviates downward, the threading distance is increased from the normal running distance.

With this,! The opening temperature changes as shown by the solid line in FIG. 2(C). Here, in order to make the area where the temperature deviates from the target temperature clear, it is necessary to discretely change the passing distance in the heating furnace at the moment the welding point passes the heating furnace outlet, but this is technically impossible. Yes, an outlying area l occurs. The length of this outlying area l depends on the maximum moving speed of the strand looper 60, but the length, ! is extremely short compared to the length of the out-of-place area when the plate passing path ^11 control is not performed, and does not lead to under-heating or over-heating of the steel plate.

〔effect〕

As described above, in the temperature control device for a heated material in a continuous heating furnace according to the present invention, the residence time of the heated material in the furnace is
By changing and adjusting the threading distance in the heating furnace instead of the threading speed, it is possible to achieve targets such as before and after the welding point, which occurred over a long range with conventional equipment, without reducing productivity or causing meandering. The present invention has excellent effects, such as being able to significantly reduce the range of temperature deviations and maintaining the temperature of the heated material at the target temperature with high precision even under stable operation.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the configuration of a temperature control device for heated materials in a continuous heating furnace according to the present invention, Fig. 2 is a graph showing the state of control of steel plate temperature by the device of the present invention, and Fig. 3 is a conventional device. It is a graph which shows the control state of steel plate temperature.

Claims (1)

[Scope of Claims] 1. Various plate-shaped materials to be heated are continuously passed through a heating furnace and heated, and the temperature of the materials to be heated at the outlet of the heating furnace is controlled to a target temperature of each material to be heated. The temperature control device for a heated material includes: a threading distance changing section that is provided in the heating furnace and expands or shortens the threading distance of the heated material; and a threading distance changing section that changes the threading distance of the heated material in the heating furnace based on the target temperature. Continuous heating characterized by comprising: a threading distance determining means for determining a threading distance; and a means for setting the threading distance determined by the threading distance determining means in the threading distance changing unit. Temperature control device for heated materials in a furnace.