NL8105608A - Detecting humming of roller set in cold strip rolling mill - by segregating hum signal from strip tension signal sensed upstream of set - Google Patents

Abstract

The arrangement is intended for detecting hum (vertical vibration) on a roller set of a cold rolling mill producing thin strip material. The hum signal is recovered from the signals produced by a strip tension sensor arranged before the set. The strip tension sensor may be connected to an electrical circuit (band-pass filters) which segregates the hum signal from the noise in the strip tension signal. The rolling operation may be controlled by a process computer which, in addition to the strip tension signal, also receives a signal representing the detected hum in order to reduce hum e.g. by reducing the rolling speed. Used in detecting hum (vertical vibration) of roller set in cold strip rolling mill. The arrangement overcomes the poor signal to noise ratio experienced when attempting to detect the hum by a microphone placed near the roller set gap, or by a vibration sensor on top of the roller set frame.

Description

φ ψ * HO 466, /.

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ROLLER DETECTOR

The Applicants mention as inventors:

Ing. Marius WOUTERS in Castricum and Ir. Herman Gerhardus RAVE in Alkmaar 5 The invention relates to a method and device for detecting hum on a rolling mill from a rolling mill "for cold rolling of thin steel sheet. In the cold rolling of thin steel sheet, it appears in particular with the end mill that very high speed gives the last reduction, in order to be able to prevent an annoying hum. By hum here is meant a vertical vibration of the rollers and the frame of a rolling mill stand. This hum appears to have a relatively constant frequency.

The consequences of hum are: 1. inadmissible thickness variations in the rolling stock that are visible especially after tinning; 2. greater risk of tire breakage resulting in damage to rollers, rolling stock and rolling stock; 3. Unfavorable influence on the life of the stretch roller bearings.

The cause of hum is not entirely clear, and the occurrence of hum cannot always be completely prevented. Attempts have been made by various researchers to detect hum before it takes on excessively large values, such that through interventions in the rolling process - e.g. reduction of rolling speed - the hum can be suppressed in time.

The following detection methods have been tested: 1. a microphone placed near the roll gap of the rolling stand.

However, this causes drawbacks in the signal processing (especially with regard to the signal-to-noise ratio); 2. a vibration sensor placed on the mounting piece of the bearing 30 of the upper support roller. However, this causes drawbacks when the roller is changed; 3. a vibration sensor on top of the roller frame (compare 8103608/2 2 * HO 466 f 1 Luxembourg patent 82911 of November 4, 1980). However, this causes drawbacks in signal processing due to a poor signal-to-noise ratio.

The object of the invention is to overcome the drawbacks mentioned and a 5. provide reliable detection for hum generation. The invention is based on the insight derived from an observed relationship between humming and the simultaneous occurrence of tensile force variations in the rolling stock before and after the respective rolling mill.

According to the invention it is proposed to use the hum signal.

derive from the tensile force meter in front of the entrance side of the rolling mill stand. Such a tensile force meter is normally already located between the last and the penultimate rolling mill and consists of a roller with pressure force sensors pressed against the rolling stock. By guiding the rolling stock over the track roller at a fixed angle, the tensile force in the rolling stock on the track roller is measured as compressive force with the above-mentioned sensors.

It is essential for the application of the invention that the pressure force sensors can follow the frequency of the hum signal. According to a further elaboration of the inventive idea, the tensile force meter is connected to an electrical circuit to detect the hum signal from the noise in the tensile force signal.

In order to obtain more insight into the nature and magnitude of the hum signal, the said electrical circuit preferably comprises a hand-pass filter whose center frequency is matched to the frequency of the hum signal and a peak value detector, as well as a device for reading the hum level. to make.

The invention will be explained in more detail below with reference to the appended drawing.

Fig. 1 is a schematic side view of the last and penultimate rolling mill from a cold rolling group and a tensile force gauge placed in between, viewed from the operating side.

Fig. 2 shows a sketch of the tensile force meter as seen according to arrow II-II in fig. 1.

Fig. 3 shows in block diagram a circuit for processing the signals obtained from the tensile force meter.

Fig. 4 'shows in a block diagram a circuit for processing the hum signal contained therein / 3 810ÖS08 t' HO 3 HO 466 / r.

Fig. 1 shows two end- usual in a cold strip rolling mill

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rolling stands 1 and 2. The cold rolling of the rolling stock 3 takes place continuously in a group of four or five placed one behind the other 5. rolling mills. In order to achieve the necessary pressure for the very high reductions, quarters with relatively thin stretching rollers and thick support rollers are used. The reduction is promoted by maintaining a draw between the rolling stands in the material. After the last rolling mill stand 1 - also under tension - the strip is rewound on a reel (not shown 10) into a roll.

The tensile force in the material is measured by means of a tensile force meter 4, including a roller running against the material.

This tensile force meter 4 is schematically shown in front view in Fig. 2. The belt 3 runs at a fixed angle over a roller 40. This roller 40 is rotatably received at bearings 41 and 42 at both ends. Each housing of these bearings rests on a pressure box 43 resp. 44 (such pressure boxes are known and contain, for example, a centrally rejuvenated pressure pin, on the side of which 20 one or more strain gauges are attached). The tension in the belt 3 causes a vertical force distributed over the roller roller 40, which is exerted on the two pressure boxes 43 and 44 as force K1, respectively. K2 manifests.

These forces KI and 12 are converted into electrical signals by means of strain gauges. It has been found that when a hum occurs in a certain frequency range, a bromine occurs in the pull signal.

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Pig. 3 shows in block diagram the circuits connected to the tensile force meter 4 (fig. * 1) to process the signal obtained therefrom. The signals obtained from the pressure boxes 43, 44 (Fig. 2) are thus the two tensile force signals between the last and penultimate rolling mill stands. Both of these pulling force signals, namely that of the drive side and that of the operating side of the roller group, are applied to the existing pulling force signal processing. This existing circuit comprises two amplifiers 51> from which the unfiltered pull signal is supplied on the one hand to a pull signal processing 52 to provide a clear pull / 4 810: 208 4 HO 466 / ti indication, and on the other to an extension of the existing circuit , consisting of a hum signal processing 53

As is customary today, the rolling is carried out under the control of a process computer which continuously intervenes in the rolling process in 5 different ways. In the circuit of Fig. 3, this computer is indicated by 54. Both the pull signal and the buzz signal are applied as input signals to this computer. It is schematically indicated that the output of the computer 54 is connected to the rolling group, for example, both rolling mills 1 and 2 shown in Fig. 1 to intervene in the rolling process.

Fig. 4 shows in block diagram the hum signal processing 53 of. Fig. 3 in more detail. The input terminals 61 and 62 are connected from the drive side respectively. operating side of the roller group the unfiltered tensile force signals. coming from the output of amplifiers 51 in. In each channel, a band-pass filter 63 resp.

64 to isolate the buzz signal from the pull signal. The center frequency of the filters can be adjusted to the t hum frequency, which in practice appears to be around 150 Hz.

The outputs of both filters 63 and 64 are connected to two peak value determiners 65 and 66. Up to this point, the circuit has been implemented equally for both signals from the pressure boxes 43 and 44. The two output signals from the peak value determiners 65 and 66 go to a maximum sensor 68 which, of both signals, only transmits the largest signal. This hum signal goes via a line buffer (not shown) to an indicating instrument 69. This instrument contains, for example, an LED line display for visualizing the hum level to the operator of the relevant end-rolling group.

The hum signals originating from the bandpass filters 63 and 64 are also supplied to the process computer 54 via a circuit 67 in which a rectifier and a mediator are included - thus in processed form, so that a correlated signal is produced. Depending on the magnitude of the buzzing signal, this computer 35 may intervene in, for example, the rolling speed with the aim of reducing the humming.

Where necessary, galvanic isolation between different parts of the circuit is provided wherever necessary.

8103608/5

Claims (6)

5 ‘HO 466: ι • t sssssssssssssssssrssssss 1. Method for detecting hum on a rolling mill from a rolling mill for cold rolling of thin steel sheet, characterized in that the hum signal is derived from a 5. rolling stand "standing tension meter. 2. Device for detecting hum on a rolling mill from a rolling group for cold rolling of thin steel plate, in which a tensile force meter is placed in front of the rolling mill, characterized in that the tensile force meter is connected to an electrical circuit to switch off the hum signal. detect the noise in the pull signal. Method for detecting hum as claimed in claim 1, wherein the rolling process is carried out under the control of a process computer, characterized in that a signal-correlated sig-15 sew is fed to the process computer in order to influence the rolling process in the sense that the humming decreases. 4. Device as claimed in claim 2, wherein the roller group is connected to a process computer, characterized in that the output of the electrical circuit for detecting the hum signal from the noise in the pulling force signal is connected to the process computer. Device as claimed in claim 2, characterized by an electrical circuit with a banddorate filter - the center frequency of which is tuned to the frequency of the hum signal - a peak value determiner, a maximum follower and a device for visualizing the magnitude of the hum level. 8. O s 3 O 8