Technical staff for magnetic particle inspection machine equipment peak problem explanation

Portable magnetic particle flaw detection machine is the most common equipment to detect whether the workpiece has defects, and its measurement accuracy requirements are quite high. When the flaw detection machine is used for workpiece defect detection, the current needs to be set according to the maximum cross section of the flaw detection workpiece. So how should we set the magnetization current of the magnetic particle flaw detection machine is the most appropriate? Today, Su magnetic flaw detection machine manufacturers to discuss with friends:

1. How to set the maximum output value of magnetization current of the flaw detection machine?

In order to maximize the inspection accuracy of the flaw detection machine, the magnetizing main transformer, the core component that provides magnetizing current, must be able to provide low voltage and high current output. In addition, according to the magnetic properties of the materials used in the workpiece, the size, shape, surface condition, defects and other factors, determine the inspection method, magnetic field direction and magnetic field strength of the magnetic particle flaw detection machine, and the effective detection range. Therefore, when selecting the magnetization current value, it is necessary to follow the magnetization specification, so that the magnetic field strength is controlled within a reasonable range, that is, the calibration magnetization current needs to reach the maximum output value.

2. What determines the maximum output value of magnetization current?

The maximum output value of magnetization current is the key to the magnetization of the workpiece, which in addition to being determined by the value of the ammeter, is also affected by factors such as the transformer or shunt, sampling resistance shunt to the ammeter value, so the calibration magnetization current needs to be verified together with the calibration ammeter to detect the relative error of the magnetization current within the specified range.

Improvement measures for ignition factors of magnetic particle flaw detection machine:

1. For the raised high point generated in the process of wheelset pressing and unloading, the raised high point is eliminated as much as possible through manual grinding to reduce the occurrence of shaft end surface ignition. The inspection personnel of the magnetic particle inspection machine self-inspect the axle end face before the inspection. Once the raised high point is found, the grinding method is adopted to deal with it, so as to eliminate the phenomenon that the axle end face is not closely adhered to the clamping device of the inspection machine as far as possible.

2, for the axle center hole edge and shaft end of the three-hole edge of the metal accumulation during the processing process can be adopted manual grinding method to eliminate the high point as far as possible; In addition, the small amount of iron filings adsorbed by the axle during the production and processing of the axle should be wiped by the inspection personnel, and the inspection can be carried out after the axle is wiped clean; As far as possible, reduce the convex high point of the axle center hole edge and the three holes at the shaft end, and improve the contact tightness between the shaft end and the magnetic particle inspection machine clamping device.

The portable magnetic particle flaw detector uses thyristor as the current control valve

The stepless speed regulation of the magnetized coil in the portable magnetic particle flaw detection machine is to change the direction of the conduction current of the coil by changing the two-way triggering Angle of the thyristor, so that the magnetization current of the magnetized coil can be adjusted without poles. So what is the most critical thyristor?

Thyristor, also known as thyristor, is an active switching device, can achieve AC contactless control, is a small current to control large current, small voltage to control large voltage, usually it is a non-conducting state, until a small control signal to trigger it to switch on, and once switched on, even if the withdrawal of the trigger signal, it also keeps on, and to make it off. The reverse voltage can be added between the anode and cathode or the current flowing through the thyristor diode can be reduced to a certain threshold below, while the thyristor in the triggered state there will be no spark generation, while the trigger action is fast, small size, simple structure, long service life, high reliability, wide range of use, thyristor is divided into one-way and two-way two kinds. Unidirectional thyristor is equivalent to three PN junctions in series and leads out anode A and cathode K from both ends, and leads out control pole G from the middle P pole; Bidirectional thyristor is a combination of two unidirectional thyristors in reverse parallel, sharing a control signal at the same time.

Inspection machine daily electrical insulation performance test:

The high voltage output test terminal is connected to the measured object, and the tester should display a certain value at this time. When testing insulation resistance, it must be gradually changed from low resistance to high resistance to ensure the accuracy of measurement. The insulation strength is tested by HY267 type voltage resistance tester, and the tester is adjusted to the corresponding range according to the test voltage, leakage current and test time of the tested object. Turn on the power and start the tester. Slowly turn the Voltage Adjustment knob in a clockwise direction. When the indicating value of the voltmeter reaches the set voltage value, if no excess leakage occurs within the set time, it indicates that the measured insulation strength meets the requirements. When the insulation strength of the measured product is not enough, the leakage current is greater than the set value, the output voltage is automatically cut off, and the "over-leakage" warning is issued, the buzzer is sounded, and the "over-leakage" indicator is lit.

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