JPH032930B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to extraction of a heating furnace in a rolling equipment in which a plurality of continuous rolling mills are disposed downstream of a heating furnace that allows a plurality of raw materials to be placed on a hearth that moves integrally and extracted sequentially. Regarding control method. BACKGROUND ART In rolling equipment for seamless steel pipes, sections, etc., a large number of materials to be rolled are present in a rolling line consisting of a heating furnace and a plurality of rolling mills. In this way, in rolling equipment, productivity can be improved by shortening the rolling cycle time for each piece of material. However, in the above-mentioned conventional rolling equipment, operations rely on the operator's experience and intuition, and it is impossible to improve productivity to the ideal limit. In addition, when performing extraction control of a heating furnace in a rolling facility, it is desired to provide a control method that is highly versatile, highly reliable, and has a low calculation load. The present invention provides an extraction control method for a heating furnace in a rolling facility that is highly versatile, reliable, and can optimize the operating status of the entire rolling line and improve productivity using a control method that requires low calculation load. The purpose is to In order to achieve the above object, the present invention has a plurality of continuous rolling mills arranged downstream of a heating furnace that allows a plurality of raw materials to be placed on a hearth that moves integrally and extracted one after another. In the extraction control method of a heating furnace in a rolling equipment, the following rolling cycle time is determined for the next material to be extracted from the heating furnace, from the start of rolling in each rolling mill to the completion of rolling preparation for the subsequent material, and the For the next extraction material or the latest extraction material, find the heating network cycle time that is sufficient to apply the specified heating to each material, and use the maximum value of each rolling cycle time and heating network cycle time as the extraction cycle time of the next extraction material. , the next extraction material is extracted during this extraction cycle time. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a control system diagram showing an embodiment in which the present invention is applied to rolling equipment for seamless steel pipes. That is, this rolling equipment is a seamless steel pipe rolling line using the Mannesmann-plug mill system, in which the material heated in a heating furnace 11 is pierced and rolled in a piercer 12, expanded and rolled in an elongator 13, and then rolled in a plug mill 14. It is rolled to a length that is approximately equal to the product wall thickness, the inner and outer surfaces are polished by two reelers 15, and at the same time, the tube is slightly thinned and expanded, and finished to a predetermined outer diameter by a sizer 16 to form the final product. Become. The heating furnace 11 is of a rotary hearth type, and a plurality of raw materials can be placed on the hearth that moves integrally and extracted one by one. Here, in the above rolling equipment, the heating furnace 11
is controlled by a heating furnace control device 21, and each mill 12 to 16 is controlled by each rolling mill control device 22 to 26, respectively. Extraction results of materials obtained in the heating furnace control device 21,
The rolling results of the material obtained in each of the rolling mill control devices 22 to 26 are transmitted to the calculation device 27. The calculation device 27 calculates the optimum extraction cycle time of the next extraction material in the heating furnace 11 as described below, and can transmit the extraction time of the next extraction material to the heating furnace control device 21. The calculation operation of the calculation device 27 is as shown in FIG. That is, the calculation device 27 first predicts and calculates each rolling cycle time MCT from the start of rolling in each mill 12 to 16 to the completion of rolling preparation for the subsequent material for the next extracted material from the heating furnace 11 based on the rolling schedule. . Here, the rolling cycle time MCT is defined as the time from the start of rolling to the completion of rolling preparation in the rolling start signal P ₁ and next material rolling preparation completion signal P ₂ shown in FIG. Therefore, if a preceding material of the same lot with the same material, dimensions, etc. as the next extracted material has already passed through each mill, the actual rolling cycle time MCT collected in each rolling mill control device 22 to 26 is Each predicted rolling cycle time MCT is calculated based on the rolling speed, rolling length and required idle time at each mill 12 to 16 if no preceding material from the same lot as the next extraction material has passed through each mill. Each predicted rolling cycle time MCT is calculated based on the following. In other words, the above rolling cycle time MCT is
This is the cycle time truly required for rolling in the relevant mill. Therefore, the time between the completion of preparation for rolling the next material and the start of rolling of the relevant mill is wasted idle time for that rolling mill, and it is desirable that this wasted time be reduced to zero in all mills. However, the rolling cycle time for each mill is
Since the MCT is different, it is impossible to reduce the above wasted time to zero in all mills. Therefore, if the wasted time in the mill with the longest rolling cycle time, that is, the network equipment, is reduced to zero,
It is possible to improve productivity the most within a given rolling schedule. This simply means that the next extraction material can be extracted from the heating furnace 11 at the rolling cycle time MCT of the mill with the largest rolling cycle time MCT. However, when extracting the next extraction material from the heating furnace 11 as described above, if the extraction cycle time is short, each material may not be sufficiently heated and soaked in the heating furnace 11, which is not desirable in terms of product quality. This results in a situation where there is no such thing. Therefore, the calculation device 27
Based on the rolling schedule, the next extracted material or the latest extracted material in the heating furnace 11,
Calculate the heating network cycle time HCT sufficient to apply the specified heating to each material. That is, each calculation device 27 calculates each heating cycle time that is sufficient to apply a predetermined heating to each material in the heating furnace 11.
CT _n is calculated based on the diameter D _n and length L _n of each material as follows: CT _n = f (D _n , L _n ) (1). The heating cycle time is determined by the dimensions (in this example, the billet diameter and billet length) of each material (steel billet). However, the formula changes depending on the capacity, structure, etc. of the heating furnace. For reference, the specific method for calculating the heating cycle time CT _n in this example is as follows:
(1)′. CH _n =K ₁・D _n (D _n +K ₂ ) (D _n +K ₃ )/R ₁
・K ₄ −L _n /K ₄ −L ₁ …(1)′ K ₁ , K ₂ , K ₃ , K ₄ : Constant value D _n : m-th billet diameter from the extraction side L _n : m-th billet diameter from the extraction side Length of the billet L ₁ : Length of the billet closest to the extraction side R ₁ : Number of charging rows of the billet closest to the extraction side The heating net cycle time HCT is the net length of each billet determined by equation (1)' above. This is the maximum value in the cycle time. That is, the above-mentioned heating network cycle time HCT is calculated by HCT=MAX( _CT1 ... _CTn ... _CTo )...(2). Next, the arithmetic unit 27 determines the maximum value of each rolling cycle time MCT and heating neck cycle time HCT determined as described above as the optimum extraction cycle time of the next extraction material. Furthermore, the calculation device 27 adds the above-mentioned optimum extraction cycle time to the latest actual extraction time of the heating furnace 11 transmitted from the heating furnace control device 21, determines the next material extraction time, and determines the next material extraction time. is transmitted to the heating furnace control device 21. The heating furnace control device 21 operates the heating furnace 11 to extract the next extraction material at the above extraction time. In the above embodiment, the rolling start signal and next material rolling preparation completion signal that determine the rolling cycle time MCT in each of the mills 12 to 16 are defined as shown in Table 1, respectively.

【table】

[Table] Next, Figure 4 A and B have a diameter of 300 mm, respectively.
The length of the material is 2269mm, the outer diameter is 341.09mm, the thickness is 12.19mm,
Histogram showing the relationship between the wasted time of the netting equipment and the number of materials N using the operating method of the present invention, and the relationship between the dead time of the netting equipment and the number of materials N using the operating method of the present invention when rolling into a steel pipe with a length of 1250 mm It is. According to Fig. 4 A and B, the average dead time is 0.96 seconds in the case of the conventional method, but the average dead time is reduced to 0.47 seconds according to the present invention, and the productivity of the entire rolling equipment is improved. It is recognized that this can be significantly improved. Further, according to the present invention, it is possible to apply it to a manufacturing process using a plurality of rolling mills, so it is highly versatile. Furthermore, according to the present invention, the rolling processing time MCT is predicted and calculated by focusing only on the next rolled material in the furnace.
It can be calculated by reflecting it in MCT calculation, and the prediction accuracy is high and reliability is high. Further, according to the present invention, since the rolling process prediction calculation is performed only for the next extraction material in the heating furnace, the calculation processing load can be reduced. Further, according to the present invention, since the heating network cycle time is calculated only from the dimensions of the steel billet,
Since the calculation results are the same for steel pieces in the lot having the same dimensions, it is possible to reduce the number of calculations. The present invention is also applicable to rolling equipment for seamless steel pipes using the mandrel mill method and the Atsel mill method, and is further applicable to rolling equipment for various types of long steel rolling, wire rod rolling, and the like. Note that this method can be applied regardless of the number of rolling mills arranged in the rolling equipment, and the greater the number of rolling mills, the greater the effect can be obtained. As described above, the present invention provides rolling equipment in which a plurality of consecutive rolling mills are arranged downstream of a heating furnace that allows a plurality of raw materials to be placed on a hearth that moves integrally and extracted sequentially. In the extraction control method for a heating furnace, for the next material to be extracted from the heating furnace, each rolling cycle time from the start of rolling in each rolling mill to the completion of rolling preparation for the subsequent material is determined, and the next material in the heating furnace is For the extracted material or the latest extracted material, find the heating network cycle time that is sufficient to apply the specified heating to each material, set the maximum value of each rolling cycle time and heating network cycle time as the extraction cycle time of the next extracted material, and calculate the extraction cycle time for the next extraction material. Since the next extraction material is extracted at cycle time, it is possible to optimize the operating conditions of the entire rolling line and improve productivity using a control method that is highly versatile, reliable, and requires low calculation load. .

[Brief explanation of the drawing]

Fig. 1 is a control system diagram showing an embodiment in which the present invention is applied to rolling equipment for seamless steel pipes, Fig. 2 is a flow chart showing the control procedure of the arithmetic unit in the embodiment, and Fig. 3 is a control system diagram showing an embodiment in which the present invention is applied to rolling equipment for seamless steel pipes. An explanatory diagram showing the definition of the rolling cycle time, FIG. 4A is a histogram showing the relationship between the wasted time of the netting equipment using the conventional method and the number of materials, and FIG. This is a histogram showing the relationship between 11... Heating furnace, 12... Piercer, 13... Elongator, 14... Plug mill, 15... Reeler,
16...Sizer, 21...Heating furnace control device, 22-
26...Rolling mill control device, 27...Calculation device, MCT
…Rolling cycle time, HCT…Heating network cycle time.

Claims (1)

[Claims] 1. In a heating furnace extraction control method in a rolling facility in which a plurality of continuous rolling mills are arranged on the downstream side of a heating furnace that allows a plurality of raw materials to be placed on a hearth that moves integrally and extracted sequentially. For the next extracted material from the heating furnace, calculate each rolling cycle time from the start of rolling in each rolling mill to the completion of rolling preparation for the subsequent material, and also calculate the next extracted material or the latest extracted material in the heating furnace. , find the heating network cycle time that is sufficient to apply the specified heating to each material, set the maximum value of each rolling cycle time and heating network cycle time as the extraction cycle time of the next extraction material, and use this extraction cycle time to extract the next extraction material. A method for controlling extraction of a heating furnace in a rolling facility, characterized by: