Electromagnetic coil working principle

The electromagnetic coil is established by the presence of a magnetic field around the wire, which is wound into a spiral-shaped reinforcing magnetic field, that is, the minimum magnetic field is used to achieve the highest magnetic field strength, and the wire coated with a layer of insulating varnish is used instead of the ordinary wire to save space. .

Electromagnetic forming can effectively improve the forming properties of lightweight alloys, and the coil structure is one of the key factors affecting the forming quality. It is necessary to determine the distribution of the electromagnetic force according to the needs of the deformation part of the workpiece and design a coil suitable for it.

The working principle of the electromagnetic coil is electromagnetism.

The direction of the magnetic field can be determined according to the "right-handed screw rule" or "Ampere's rule one": hold the straight wire with your right hand and point the thumb at the direction of the current, then the direction of the other four fingers is the circumference of the magnetic line. direction. In fact, the magnetic field produced by this straight wire is similar to the effect of placing a small magnet with a NS pole end to end around the wire.

If a long metal wire is wound in a direction on a hollow cylinder, the object formed is called a solenoid. What if you energize this solenoid? After energization, each turn of the solenoid generates a magnetic field, the direction of which is shown by the circular arrow in Figure 2. Then, at the position between the adjacent two turns, the total magnetic field cancels out due to the opposite direction of the magnetic field; and inside and outside the solenoid, the magnetic fields generated by each of the turns are superimposed on each other, eventually forming a magnetic field shape. It can also be seen that the shape of the magnetic field outside the solenoid and the shape of the magnetic field generated by a magnet are the same. The magnetic field inside the solenoid just forms a closed magnetic field line with the external magnetic field.

The solenoid is shown as a row of upper and lower rows, as if the solenoid was cut from the middle. There is a cross in the upper row, indicating that current flows into the interior of the screen; a black dot in the lower row indicates that current flows outward from the inside of the screen.

An example of an application of electromagnetism is an electromagnet commonly used in laboratories. In order to carry out some scientific experiments, a strong constant magnetic field is often used, but only ordinary solenoids are not enough. To this end, in addition to winding the coil as much as possible, two opposing solenoids are placed close together such that their N and S poles are opposite, such that a strong magnetic field is created between the two wire packs. In addition, pure iron (called yoke) is placed in the middle of the line package to gather the magnetic lines of force and enhance the magnetic field in the middle of the line package.

For a very long solenoid, the internal magnetic field is calculated by the following formula: H = nI

In this formula, I is the current flowing through the solenoid, and n is the number of solenoid turns per unit length.