SU1740984A1 - Method for measuring length of moving ferromagnetic material - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure the length of moving ferromagnetic materials, such as rolled metal, wire, cables. When measuring the length of the ferromagnetic material, a magnetic mark is applied to it after passing the previous mark of the base distance. The label is applied by continuous magnetization by an alternating magnetic field with a frequency ti, and the next label by an alternating magnetic field with a frequency fa. Further, the whole process is repeated. Recording changes in the frequency characteristics of the field of magnetization of the material makes it possible to avoid false alarms of the reading device when exposed to external factors.

Description

The invention relates to a measurement technique and can be used to measure the length of moving articles made from ferromagnetic materials, such as rolled products, wires, cables.

Methods are known for measuring the length of moving ferromagnetic materials using mechanical devices. Such methods are characterized by a large measurement error.

The closest to the technical essence of the present invention is a method for measuring the length of a moving ferromagnetic material, which means that a magnetic mark is applied to the ferromagnetic material by continuously magnetizing the ferromagnetic material by one polarity of the magnetic field during the beginning of the mark of the base distance. Each subsequent label is applied with a polarity change of the magnetization field. With the aid of a reader, the moments of polarity reversal of the magnetization of the material are recorded, the number of which determines its length.

However, when implementing this method, false positives of the reading device are possible, due to the change in the gap between the sensitive element and the material, external electromagnetic interference, etc. For example, when using magnetic heads as a sensitive element of a reading device at the moment of changing the gap between the material and the sensitive element in the latter, an electrical impulse similar to the impulse that occurs when changing the polarity of the material magnetization can be induced. As a result, the accuracy in measuring the length of the material decreases.

The aim of the proposed method is to increase the measurement accuracy and noise immunity.

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The goal is achieved in the method that a magnetic mark is applied to a ferromagnetic material after passing the previous mark of the base distance, the number of which determines the length of the material, the mark is applied by continuously magnetizing the ferromagnetic material with an alternating magnetic field with a frequency fi during the passage of the mark of the base distance, and the next mark - by an alternating magnetic field with a frequency f2 followed by repeating the process described above. Registration of changes in the frequency characteristics of the field of magnetized material allows you to avoid false alarms of the reader when exposed to external factors. As a result, the measurement accuracy is improved.

The frequencies fi and f2 should not be multiple to each other in order to avoid the influence of harmonic components.

The drawing shows a diagram of a device for measuring the length of a moving ferromagnetic material, an implementation method.

The method is carried out as follows. The generator 3 generates an electric current of frequency fn, which is converted into an alternating magnetic field by the magnetic head 1. The head 1 magnetizes the ferromagnetic material 2 moving in the direction indicated by the arrow 2. The magnetized area fi the section of the ferromagnetic material 2 reaches the reading head 4 from the magnetic head 1, which, under the influence of the magnetization field of the ferromagnetic material 2 produces an electrical signal of the same frequency, the signal is amplified by the amplifier 5 and after upaet at unit 6 and a control register, which registers the occurrence fi the frequency of the electrical signal and outputs the control signal to the generator 3. Under the influence of the control signal generator 3 starts to produce the frequency f2. The process described above is repeated. The number of frequency changes is counted by a counter 7 connected to the unit 6 of registration and control. Thus, the length of the ferromagnetic material 2 is equal to the product of the base distance and the number accumulated by the counter 7.

Using the proposed method of measuring the length of moving ferromagnetic materials provides the following advantages compared with existing methods:

increased measurement accuracy by increasing noise immunity;

reducing the requirements for maintaining a constant gap between the sensitive element and the ferromagnetic material;

reducing the harmful effects of external electromagnetic fields.

Claims (2)

Claims The method of measuring the length of a moving ferromagnetic material is that a magnetic mark is applied to the ferromagnetic material by continuous magnetization after passing the previous mark of the base distance, and the length of the material is determined by the number of marks, characterized in that and noise immunity, the label is applied by magnetizing the material with an alternating magnetic field, with a frequency fi during the passage of the base distance, and the next label with a frequency fa with the subsequent repetition. 2. A method according to claim 1, characterized in that the frequencies f i and f2 are not multiple to each other. 0