How electromagnets work
When an iron core is inserted into a energized solenoid, the core is magnetized by the magnetic field of the energized solenoid. The magnetized core also becomes a magnet, so that the two magnetic fields are superimposed on each other, thus making the solenoid much more magnetic. To make the electromagnet more magnetic, the iron core is usually hoof shaped.
But notice that the coil on the hoof core is wound in the opposite direction, one side is clockwise, the other side must be counterclockwise. If the winding direction is the same, the magnetic effects of the two coils on the core will cancel each other, so that the core will not be magnetic.
In addition, the core of the electromagnet is made of soft iron, not steel. Otherwise, once the steel is magnetized, it will maintain magnetism and not demagnetization for a long time. The strength of its magnetism can not be controlled by the size of the current, and the advantages of the electromagnet should be lost.
The working principle of the brake electromagnet is that when the winding of the electromagnet is energized, the armature is drawn to the iron core and presses the brake lever through the stop in the brake to make it move, thus forcing the brake to loosen. After cutting off the coil power supply, the brake lever makes the armature out of the magnetic yoke under the action of the spring, while the brake stops the mechanism. The main technical parameters of brake electromagnet are stroke, electromagnetic suction force under a certain stroke, operating frequency and power-on duration. Operating frequency refers to the number of operations per hour; Power-on duration is the percentage of each power-on time plus the sum of each power-on and power-off time. In use, brake electromagnet and tile brake match with short stroke class; Long travel class for matching with belt brake. Brake electromagnet hydraulically transmits the electromagnetic force to the braking mechanism called hydraulic brake electromagnet.
Valve electromagnet
Electromagnet for remote operation of valves of hydraulic and pneumatic systems. It is often used in various metal cutting machine tools. The valve electromagnet does not have a reset device, and the spring in the valve body makes it reset. When the excitation winding of the electromagnet through the current, the electromagnetic suction is to overcome the spring resistance, the push rod of the valve body moves, the valve is opened; When the excitation winding power off, under the action of the reset spring, the valve body push rod will push the armature, make it move the rated stroke, the valve is closed. Valve electromagnet is divided into wet type and dry type two. The armature of an electromagnet in a wet valve works in hydraulic oil, and due to the cooling effect of the oil, it has a smaller size compared to an electromagnet with the same suction force.