CS239685B1 - Equipment for cracks and cavities discovery in steel bars - Google Patents

Abstract

The device for detecting cracks and cavities in steel bars is intended for continuous inspection of steel bars in order to prevent the processing of steel with significant cracks or cavities. The inspection according to the invention is carried out using transformers (6) with primary (5) and secondary windings (3), which are at least two and are arranged in a crosswise manner one after the other, their cores (4) are open and extended on one side. At these extended ends, the cores (4) are provided with pole extensions (9) facing each other, with which the electromagnetic circuit of the core (4) is supplemented by the measured rod (8) and the air gap. Two or three, or four secondary windings (3) of the transformers (6) are provided with two diode rectifier bridges (2) for a balancing ammeter (1), which, by its deviation from the zero position, indicates defective steel.

Description

The device is for the continuous checking of steel bars to prevent the processing of steels with various cracks or cavities.

Inspection of steels for cracks can be performed in various ways, in particular by radiation of different wavelengths. These devices, such as ultrasonic or the like, are too expensive to equip individual plants or steel cutting machines. In addition, various radiation is in most cases harmful to health and affected by contamination;

According to the invention, a device for detecting cracks and cavities in steel rods by means of electromagnetic circuits with pole extensions and limit switches is characterized in that the transformers with primary and secondary windings are at least two in succession, are cross-mounted and their cores are open on one side The open side of the core is elongated and at this elongation of each core there are pole extensions in the shape of the bars to be measured.

The open side of the core is closed by the pole pieces with the measured rod and the air gap. The secondary windings of two or three transformers are provided with two diode rectifier bridges for a balancing ammeter. In the three secondary windings, two are connected to one diode rectifier bridge and the third secondary winding is connected to the opposite diode rectifier bridge, which is for double current and increased voltage, with the ammeter in equilibrium. The current switching and opening devices consist of two limit switches, the circuit of which is interconnected, one placed in front of the transformers and the other with them.

With the device according to the invention, it is achieved that all steel bars to be processed, for example, by forging can be continuously monitored, so that defective bars are discarded before they are processed. Since the equipment requires very low production costs, it can be equipped with the starting lines of all machines for cutting or cutting steel bars, so it can not happen that the cracks in the material are discovered only on the finished product, which then has to be scrap.

The device is shown in the drawing, where Fig. 1 is a cross-sectional view of a transversely measured rod and Fig. 2 a longitudinally measured rod.

The apparatus is provided with transformers 6, each with primary 2 and secondary windings 6. These transformers 6 are at least two and are arranged in a cross-wise manner. In the case of two transformers 8, they form a right angle 8 with each other, and in the case of three transformers 8, they make an angle of 60 ° to each other.

The cores X of the transformers 6 are open and elongated on one side, thereby forming a U-shaped or illustrated a. The electromagnetic circuit of the core χ is closed by pole supports s with a measured rod a and an air gap. The secondary windings 4 of two or three transformers 4 are provided with two diode rectifier bridges 6 for a balancing ammeter 1 in the form of a Wheatstone bridge.

In the case of the three secondary windings 6, two are connected to one diode rectifier bridge 6 and the third central winding 4 is connected to an opposite diode rectifier bridge 6 for which there is a double current and an increased voltage.

The balancing ammeter J is balanced to equilibrium, but for one side of the deflection its pointer hand is considered to be smaller than for the other side. The current switching and opening devices of the transformers 8 consist of two limit switches 2, the circuit of which are interconnected with one another and one is placed before the transformers 6 and the other after them.

The transformers shown are used for fine or normal arc welding, whereby the current of the secondary welding winding 6 is changed by zooming or moving the mange shunt. However, in the present case, the power of the transformers 6 is very low, although the measuring currents are needed as much as possible.

The current of the transformers 6 need to be adjusted from the maximum current of the secondary winding £ 30 A at a maximum voltage of 0.0 µV. The sensitivity of the device at 10 A and relatively greater voltage has been tested and showed great efficiency for any air gap that in any case cracked material or cavity arises.

Since the transformers 6 are close to each other, the cross-section of the rod 6 cannot be noticeably changed. Since the rolled or cracked steel does not have this air gap exactly equal, it will always be reflected in the differential current of the secondary winding J in the two transformers 6, even if the crack is at the same angle to the two transformers 6.

With three or four transormers, it is possible to detect every change in steel damage. It is necessary that the transformers 6 can only be connected via both limit switches 2, since the successive insertion of the rod 6 between the pole pieces 6 of the transformers 6, which are connected in current, would always destroy or switch off the fuses.

It is preferred that the balancing ammeter 1 is a switch and both limit position switches would control the light signaling or marking device by color.

In the case of rolled steel for crack control and hardened steel, the two transformers 6 are on the sides and close to each other in order to cover the entire area of their width with their pole pieces 6. It almost never happens that the crack creates the same high air gap over its entire width and also the transverse cracks 3 are almost never dotted with the same amount, moreover, the pole pieces 6 of the two transformers 4 are not in the transverse plane,

In the case of rolled steel, it is preferable that the pole pieces 6 are not directly above each other, thereby elongating the electromagnetic circuit and more precisely capturing longer longitudinal cracks.

When checking flat bar steel, the current is balanced by the width, height and distance of the pole pieces 6. Since the measuring currents at a very low voltage need to be relatively large, in this case each side needs to be balanced by two wire potentiometers.

The first is for coarse balance and the second is for accurate balancing of the current. This precision potentiometer needs to be made of thick copper wire, wound on a small insulator diameter, and fitted with a friction slide. It is at least 0.000 5 Ohm for sensitivity.

Claims (1)

Apparatus for detecting cracks and cavities in steel rods by means of electromagnetic circuits with pole extensions and limit switches, characterized in that at least two transformers (6) with primary winding (5) and secondary winding (3) are cross-wise in succession, their cores (4) are open and elongated on one side and at their ends are provided with pole pieces (9) towards each other, with which the electromagnetic circuit of the core (4) and the measured air gap (8) and air gap are added. . four secondary windings (3) of transformers (6) are provided with two diode rectifier bridges (2) for balancing ammeter (1),