The commutator manufacturer introduces the principle and structure of the commutator

The commutator manufacturer introduces the principle and structure of the commutator

The commutator manufacturer says that the commutator is the part of the DC permanent magnet series motor and the single-phase series motor that can make the motor continue to rotate. When a current is passed through the coil, it is rotated by attractive and repulsive forces under the action of a magnetic field. When it rotates to balance with the magnet, the contact piece on the commutator corresponding to the original energized coil is separated from the brush, and the brush is connected with the contact corresponding to the group of coils that generate the driving force. Repeatedly, the DC motor rotates.

Without the function of the commutator, the motor can only be stuck in less than half a turn and cannot achieve continuous operation.

The commutator produced by the commutator manufacturer is structurally a ring surrounded by a plurality of formed contact pieces. The contact pieces are respectively connected with each contact on the rotor winding element. brush contact.

Most of the commutators produced by commutator manufacturers are semi-plastic commutators, which are composed of a plastic casing, a copper commutator, an insulating layer between mica sheets and a metal sleeve, as shown in the figure below. Since the insulation between the sheets is still mica sheets, not all of them are plastic, so it is called a semi-plastic commutator. Small commutators can be made without metal bushings.

The commutator segments produced by commutator manufacturers are mostly made of electrolytic copper. For commutators that require higher wear resistance and surface softening temperature, silver copper or cadmium copper can be used.

The side of the commutator segment is trapezoidal, so it needs to be stamped with trapezoidal copper bars. Most of the trapezoidal copper bars are drawn from bar. Through cold drawing, the uniformity of the size of the trapezoidal rod is ensured, and the quality of the electrolytic copper is improved. hardness. The commutator segment shown in the figure below has a downward elongated dovetail structure, which is to prevent the commutator segment from being pulled out by centrifugal force during high-speed operation. In recent years, in order to save copper, the elongated dovetail part of the commutator segment is omitted, the side of the commutator segment is embossed with concave and convex, and the upper part is made into a hook shape. This structure is also used abroad. Many of them can also withstand the centrifugal forces of the commutator at high speeds. Due to the different connection structure between the commutator and the coil head, it can be divided into two types: slot commutator and hook commutator. A slot is milled out on the convex part of the commutator segment, the coil head is embedded in the slot, and then spot welding (hot pressure welding) is performed. Make a good electrical connection to the groove wall.

When the hook type commutator is wound around the rotor coil, the coil head is wound on the hook of the commutator segment. After the coil is wound, each wire end is wound on the corresponding commutator segment hook. Press down to make a good electrical connection between the wire head and the commutator. Hook commutators are used to easily automate the process of connecting coil stubs and commutators. In small cases, the main consideration is that the wire diameter of the high-power motor coil is thick, and the winding is difficult. When the number of commutator pieces is large, the width of the hook should be narrow, and the adjacent wire ends are easily short-circuited, so it is mostly used for low-power motors.

The casing of the commutator is made of glass fiber reinforced thermosetting plastic or bakelite powder, which has high requirements on the heat resistance and mechanical strength of the plastic, and the thermal expansion coefficient is required to be as close as possible to the copper commutator. The role of the metal bushing is to protect the plastic from mechanical stress when the commutator is pressed against the shaft.