JPH0575484B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Field of Industrial Application The present invention relates to a release detection method for detecting release of a rolled material in a rolling mill that rolls a steel plate or the like in a kiss roll state. (b) Prior art When manufacturing steel plates, especially thin steel plates, using a rolling mill,
In the latter half of the finishing stand of the hot rolling line,
Kiss roll rolling is often applied. At this time, it is very important to detect and confirm that the rolled material is released, but conventionally, after the rolled material is released in the previous stand, if the absolute value of the load including the kiss roll load changes by more than a certain value, Alternatively, a method is adopted in which, even if the absolute value is below a certain value, if the rate of change is significant, the release of the rolled material in the kiss roll stand is detected. However, in reality, it is difficult to accurately separate the initial load and the load due to plate rolling, so the method described above will continue to misrecognize the engagement status of each stand, resulting in problems such as strip bottom thrusting due to a delay in the lowering timing of the looper, etc. It can also cause operational problems. Furthermore, if the detection setting value is kept low to prevent erroneous detection of release of the rolled material, and a light rolling operation is performed on a thick steel plate that does not kiss roll, the tension at the tail end of the plate may be A load change occurs due to the shift free state, resulting in erroneous detection of release, which ultimately becomes a serious hindrance to the production of stable, high-quality products. (C) Purpose This invention not only accurately detects the release of rolled material by using the kiss roll load and the actual load obtained from the absolute value of the load immediately after release of the front stand, but also detects the release of the strip bottom. It is an object of the present invention to provide a method for detecting the release of rolled material in a rolling mill, which prevents the occurrence of operational troubles such as the above and contributes to the stable production of high-quality products. (d) Configuration The method for detecting the release of rolled material in a rolling mill according to the present invention is to detect the kiss roll load immediately before the rolled material is bitten and the rolling load of the front stage stand immediately after the release of the rolled material, in a rolling mill that waits for rolling in a kiss roll state. The difference between the load and the actual load is calculated and stored, and when the amount of change in the load of the front stand after the release exceeds a certain ratio of the actual load, release of the rolled material is confirmed. It is said that (e) Examples The method for detecting rolled material release in a rolling mill according to the present invention will be described in detail below with reference to examples. FIG. 1 is a diagram of a device for implementing the method of the present invention in a hot rolling line, and FIG. 2 is a diagram showing changes over time in the rolling load in a kiss roll rolling stand. First, in FIG. 1, 1 is a stand for kiss roll rolling (hereinafter referred to as a finishing stand);
Reference numeral 2 denotes a pre-stage stand, and a hydraulic looper 4 is disposed between the two stands, and the rolled material 3 passes from the pre-stage stand 2 through the hydraulic looper 4 and through the finishing stand 1, as shown in the figure. 5 is a load cell installed on the finishing stand 1, and the rolling load signal taken out by this is sent to the detection device A according to the present invention.
sent to. Reference numeral 6 in the detection device A is a first memory (storage device), which indicates the kiss roll load of the finishing stand 1 where the rolled material 3 is not yet bitten and is waiting for rolling in a kiss roll state, that is, the kiss roll load in FIG. A signal of load P ₀ in state T ₁ is input, and the load value is stored. In principle, this memorization timing T ₁ may be any time before the rolled material is bitten into the finishing stand 1, but in reality, the kiss roll load may change due to manual intervention correction of the rolling reduction amount, etc. There is a certain amount of variation even under certain settings, and considering detection accuracy, the timing of biting into the finishing stand 1.
It is preferable to be as close to T ₂ as possible. Such setting of the memory timing T ₁ can be done by detecting, for example, a change in the detection signal of the load cell 5 installed in the front stand 2 when the rolled material is caught in the pre-stage stand 2, and by applying this detection signal to a timer (not shown) to a predetermined value. This can be realized by inputting the operation chance command signal to the memory 6 after a time delay. A subtracter 9 receives the signal of the kiss roll load P ₀ stored in the first memory 6 and the rolling load signal from the load cell 5, and calculates the difference between the two loads.
A second memory 8 is connected to receive the output signal of the subtracter 9. The second memory 8
In the subtracter 9, the rolled material 3 is
The rolling load of the finishing stand 1 at a specific time T ₄ after the rolling material 3 is bitten, that is, the rolling load of the finishing stand 1 at a specific time T 4 after the rolling material 3 is bitten, that is, the rolling load of the finishing stand 1 further advances from the biting point T ₂ of the rolling material 3 in FIG.
_{The difference} ΔP (= _{P 1}
-P ₀ ) is calculated, accept the signal and store its value ΔP. Regarding the timing control of this operation, the detection signal that detects the release of the front stage stand 1 is applied to a timer (not shown) to have a predetermined time delay, and then inputted into the second memory 8 as a command signal for the operation chance. Just do it. The delay time is such that the rolling load on the finishing stand 1 exhibits an unstable value for a certain period after the pre-stage stand 2 is released due to the tension-free effect of the tail end of the plate due to the release. It is preferable to set it so that the load value after the elapsed time is stored. A gain of 10 is connected to the latter stage of the second memory 8, which converts the signal output from the second memory 8 into the kiss roll load due to changes in the rolling load of the AGC (automatic plate thickness controller). Taking into account the change, it is reduced based on a constant ratio α, and is output to the next-stage comparator 12 as the load difference ΔP' shown in FIG. On the other hand, 7 is a third memory, into which the signal of the load P ₁ after the rolled material 3 is released from the front stage stand 2 is input, and the load value is stored therein. The third
Reference numeral 11 connected to the memory 7 is a subtracter, which calculates the load P ₁ after releasing the rolled material of the front stand 2, that is, at T ₄ , which is stored in the third memory 7.
A signal of the load Pm after the front stand is released, which is continuously detected by the load cell 5, is input,
As shown in Figure 2, by subtracting these two, the above load is calculated.
The amount of change ΔPm (=P ₁ - Pm) with respect to P ₁ is calculated, and this is used as a signal to the comparator 12 in the next stage.
output sequentially. The comparator 12 receives the signal from the subtracter 11, that is, the load change amount ΔPm, and the signal of the load difference ΔP' from the gain 10, and compares the two. At this time, if ΔP′ is larger than ΔPm, the second
The rolled material 3 has not yet reached the finishing stand release point _T5 in the figure, and therefore the comparator 12 does not output the final release signal. On the other hand, if ΔP' is smaller than ΔPm, the comparator 12 outputs a signal indicating that the rolled material is released from the finishing stand 1 in a state like ΔPn in FIG.
Finally, 13 is a relay, and the comparator 1
2, and only when the final release signal of the rolled material 3 in the finishing stand 1 is output, it sends a clearly visible signal to the outside, and performs AGC or finishing roll speed correction, etc. It provides switching timing for various controls related to finish rolling, or is used as an operation signal such as a lamp display. According to the above configuration, the load difference ΔP′, which is the standard for detecting release, is obtained by multiplying the actual load ΔP, which is obtained by subtracting the kiss roll load P ₀ from the actual load P ₁ at time T ₄ , by a constant ratio α. Because it is
The value is one in which the influence of the kiss roll load is eliminated, and moreover, it fluctuates appropriately depending on the magnitude of the actual load ΔP. This is explained as follows, assuming the rolling pattern shown in Table 1 and assuming that the constant ratio α is 0.5.

[Table] That is, the rolling pattern is as shown in FIG. 3A, where the kiss roll load P ₀ is 0 tons and the actual load is 1000 tons. In this case, the load difference ΔP' is calculated as 0.5×(1000−0)=500. Therefore, the moment when the 1000 ton load changes by 500 ton is recognized as ``released''. rolling pattern ()
As shown in Figure 3B, the kiss roll load P <sub>0</sub>
is 500 tons and the actual load is 700 tons.
In this case, the load difference ΔP' is calculated as 0.5×(700−500)=100. Therefore, the moment when the 700 ton load changes by 100 ton is recognized as ``released''. In this way, the present invention can be applied to any rolling pattern regardless of the magnitude of the kiss roll load, and can also accurately detect the "bite-off" point according to each rolling pattern. . It goes without saying that the method for detecting release in a rolling mill according to the present invention is not limited to the above embodiment. For example, regarding the load storage timing of a rolled material, even more reliable detection can be achieved by tracking the tail end of the material using a pulse generator or the like and storing the load value just before the material is released. Further, instead of the load signal in the detection method of the above embodiment, an alternative signal such as a load current of a mill motor can be used. (f) Effect As is clear from the above explanation, if the method for detecting rolled material release according to the present invention is implemented in a rolling mill that waits for rolling in a kiss roll state, the initial load and the load due to plate rolling can be accurately separated. By detecting this, it is possible to suppress false detection of rolled material release on the rolling stand, and prevent operational troubles such as strip bottom pushing up due to a delay in the lowering timing of the looper. Even when carrying out light rolling operation, it is possible to avoid a situation where a load change due to the tension-free state at the tail end of the plate is mistakenly detected as a release of the rolled material. Therefore, it is possible to exhibit a remarkable effect in producing stable, high-quality products.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of an apparatus for carrying out the method of the present invention in a hot rolling line, Fig. 2 is a diagram showing changes in rolling load over time in a finishing stand in a kiss roll state, and Figs. 2A and 2B are diagrams showing temporal changes in different rolling loads, respectively, and are diagrams illustrating an application example of the present invention. In the diagram, 1: finishing stand, 2: front stage stand,
3: Rolled material, 4: Hydraulic looper, 5: Load cell, 6: Memory 1, 7: Memory 2, 8: Memory 3, 9: Subtractor, 10: Gain, 11: Subtractor, 12: Comparator, 13: display.

Claims (1)

[Claims] 1. In a rolling mill that waits for rolling in a kiss roll state, the difference between the kiss roll load immediately before the rolling material is bitten and the rolling load immediately after the front stand is released, that is, the actual load, is calculated and stored, and the roll load of the front stand is calculated and stored. A method for detecting release of rolled material in a rolling mill, comprising confirming release of rolled material when the amount of change in load after release exceeds a certain ratio of the actual load.