DE19506066C2 - Process for operating a heating system for metallic goods - Google Patents

Description

The invention relates to a method for operating an ER heating system for metallic goods, the metallic Well in sequence through at least two separate heating zones to be led.

In the metalworking industry, in different production stages heating systems for metal of any kind. The warming of the me talls can act as a preparatory measure for you closing processing step, which is usually form is changing, or for post-treatment after serve a processing step. With the metallic good can be blocks, piece goods or continuous goods.

To achieve a constant quality of the processed Metal goods, in most cases it is essential that Metal goods of the same shape when leaving the heat system always about the same temperature distribution having. This can only be achieved if this metallic goods with a constant course of time is led through the heating system.

Problems arise in this regard if the matter al throughput temporarily changed by the heating system must be how z. B. if the product is interrupted can occur. In the event of a reduction in the Material throughput due to a slowdown in the front the metallic material remains longer at the pushing speed than the nominal throughput in a heating zone. If you specify one Target temperature, the z. B. on the surface of the material should be enough, the ent Set the speaking temperature as for the nominal throughput len, because of the longer stay in the heating zone the metallic good is better along its cross-section soaked, d. H. the temperature distribution within the me  Tall goods differ from that of the good at nominal throughput. This changed temperature distribution remains then also exist in the following heating zones, so that it is on End of the pass through the heating system as a whole the metallic goods can overheat.

From DE 38 09 932 C1 is a heating system with meh reren in a row one behind the other, separately tax heatable zones, for each of which a target temperature is known. In this publication, a ver drive for heating strand-shaped metallic material wrote, the reproducibility of the heater result should be ensured by that along of the strand-like material temperature gradient measured on the basis of which the heating output of heating zones is calculated is not.

This procedure is only once in use strand-like good constant cross-section sense full and can not on heating systems for general cargo are transferred, on the other hand, the problems with changed throughput is not affected.

The object of the present invention is a method of the type mentioned in the introduction, accordingly with changing material throughput metallic material any ger but more constant during a procedure The type and shape at the end of the heating section always roughly gets the same temperature distribution.

This object is achieved in the method according to the invention solved by that in each heating zone the amount of the metallic thermal energy to be supplied controlled in this way or it is regulated that for the good at the exit everyone Heat content to be achieved in relation to a heating zone certain length of the goods, regardless of the material throughput D is kept approximately the same.  

The measure is based on the knowledge that warmth hold of the metallic goods at the end of the respective heating zone must be roughly the same at the end of the heating section To obtain workpieces with the same temperature profile ten.

The method according to the invention can be implemented that the amount of metal material to be fed Thermal energy depending on the material throughput D below Taking heat losses into account is calculated. The Heat losses are subject to the metallic goods accordingly longer or shorter in each Heating section, the dependence on Material throughput D.

The method according to the invention can also be implemented in such a way that for the heat content to be reached at the exit of each heating zone, the corresponding target surface temperature T _{s of} the metallic material, which is dependent on the current material throughput D, is determined at the exit of the respective heating zone and that the surface temperature T _o present here is measured and regulated by supplying the thermal energy to the target surface temperature T _s .

Since the residence time of the metallic goods in a heating zone is higher than in Nominal throughput, in this case becomes a lower one Target surface temperature of the respective heating zone intended.

According to the invention, the supply of thermal energy can be carried out by Change in the heating output of the relevant heating zone are influenced, depending on the type of Heating system the heating temperature or the electrical Heating power is changed.  

According to the invention, the supply of thermal energy can also be carried out by Change in the operating time t of the heat energy supply in the affected heating zone. This can e.g. B. happen that depending on the material throughput D after the metallic goods have entered a heating zone a waiting time until the heating power starts is established.

Both of the above measures can also be taken together be applied.

According to the invention, in order to determine the dependency of the surface target temperature T _s on the material throughput D for a process sequence in the respective heating zones, at least one pair of values of the variables target temperature T _s and material throughput D optimized for the desired operating result is determined. The remaining values are interpolated or extrapolated.

The calculated depending on the material throughput D. Values of thermal energy can be preferred Embodiment of the invention for a representative Number of values of material throughput D stored and can be called up if necessary.

Analogously, according to the invention, the values of the target temperature T _s determined empirically and / or arithmetically as a function of the material throughput D for a representative number of values of the material throughput D can be stored and called up if necessary.

Since as a result of the method according to the invention the heat content of the metallic material is almost the same for all values of the material throughput D after leaving a heating zone, the change of the target surface temperatures T _s can take place without a time delay when the material throughput D changes.

All of the aforementioned measures relate to a metallic good of the same type and shape. If a good with a changed size, e.g. B. changed cross-section, or other material properties are heated, then new values must be determined for a further process flow to calculate the dependence of the surface target temperatures T _s on the material throughput D. If the amount of heat energy to be supplied is controlled depending on the material throughput D, the changed properties of the goods must be taken into account in the calculation.

The following is now based on a drawing that after a Embodiment of the method according to the invention determined Dependency which approximately correspond to the target temperatures the surface temperatures of a metallic good from Material throughput D in the individual heating zones of one heater system clarifies.

The figure shows a diagram with one at the end Temperatures measured on the surface of a heating zone metallic good for two different values of the mate throughput in a heating system with six heaters zones.

Surface temperatures T _{o of} the metallic material in degrees Celsius are plotted on the ordinate. The individual heating zones are shown on the abscissa. The data were recorded on a heating system with six heating zones
The surface temperatures T _o were measured at the exit of a heating zone. The solid line connects the surface temperatures T _o which were recorded with a material throughput D of 100% of the nominal throughput.

The dashed line 2 represents the corresponding surface temperatures T _o with a material throughput D of 10% of the nominal throughput. Because of the lower material throughput D the dwell time of the metallic material in the individual heating zones is increased compared to the nominal throughput, the metallic material is warmed better , ie the temperature gradients across the cross-section of the metallic material are lower. So that the metallic material has the same heat content at both throughput values, the amount of heat energy to be supplied must be reduced at smaller throughput values. This is done in this example according to the invention in that the surface temperatures T _o are kept lower by specifying reduced surface target temperatures T _s .

Therefore, the surface temperatures T _{o of} the dashed line 2 are initially below those of the solid line 1.

They only approach at the end of the heating section Both curves 1 and 2 face each other, because at the end of the heating the temperature gradient along the cross are very low.

Reference list

1 surface temperature with material throughput 100%
2 surface temperature with material throughput 10%

Claims (8)

1.Procedure for operating a heating system for metallic goods of any type and shape which remains constant within a process sequence, the metallic goods being passed successively through at least two separate heating zones with the aim of having a certain heat content at the exit of each heating zone, based on a specific length of the Good to achieve, characterized in that for the heat content to be reached at the exit of each heating zone, the corresponding target surface temperature T _{s of} the metallic material, which is dependent on the current material throughput D, is determined at the exit of the respective heating zone and that the surface temperature T _o present here is measured and regulated by supplying the thermal energy to the target surface temperature T _s . 2. The method according to claim 1, characterized characterized in that the supply of thermal energy by Change in the heating output of the relevant heating zone being affected. 3. The method according to claim 2, characterized characterized in that the supply of thermal energy by Change in the heating temperature of the relevant heating zone being affected. 4. The method according to claim 2, characterized characterized in that the supply of thermal energy by Change in the electrical power of the concerned Heating zone is affected. 5. The method according to claims 2, 3 or 4, characterized in that the supply of thermal energy by changing the operating time t of the heat energy supply is affected in the heating zone in question. 6. The method according to claim 1, characterized in that for determining the dependency of the surface target temperature T _s on the material throughput D for a process in the respective heating zones at least one optimized pair of values for the desired operating result of the variables target temperature T _s and material throughput D and the other values are inter- or extrapolated. 7. The method according to claim 1, characterized in net that depending on the material throughput D calculated values of thermal energy for a representative Number of values of material throughput D stored and can be called up if necessary. 8. The method according to claim 6, characterized in that the empirically and / or computationally determined values of the target temperature T _s for a representative number of values of the material throughput D are stored as a function of the material throughput D and are retrieved if necessary.