Troubleshooting of medical power tools

A dental drill is a type of pedal-type push button switch that controls the motor power supply. The failure of this dental drill is mainly in the motor and flexible shaft transmission. An electric motor with a dental drill is mounted on the cantilever of the rotatable main column, and the power supply is connected through two flat conductive rings and spring contact fingers of the column.

Due to frequent contact and rotational friction, the conductive ring and the spring are easily worn or disassembled, and the spring is often in a powered state, and is prone to deformation, failure, or breaking after long-term heating, which may cause a power-supply disconnection fault. The series motor of the dental drill is erected and its armature shaft end is often supported by a steel ball. Attention should be paid to its resetting during maintenance, inspection and assembly. Otherwise, the relative position of the armature will sink after the device is installed, and the lighter will not start. In severe cases, the commutator will be short-circuited and burned.

The structure of the gypsum chainsaw motor, switchgear, and casing is basically similar to that of a hand drill, but due to the need to oscillate back and forth for cutting, the structure of its working head is different from that of a hand drill. Common faults In addition to the motor, the wear and jamming of the swing mechanism of the work head is mainly involved.

The steps for the rewinding of the winding of a motor drill are as follows: Removal of the primary windings In the removal of the primary windings, the primary diameter and the number of windings of the stator or rotor winding, the pitch of the rotor windings and The welding position of the reversing plate, the size of the stator winding, the position of the lead wire, and the position of the brush.

Rewind the stator windings. Take out a complete stator winding flattened and use the measured result as the dimension of the winding die. Rewind the stator winding according to the wire diameter and turns of the original winding. The two windings are connected at the end. Finally, check the wiring. When verifying, you can place a nail in the magnetic pole and pass low voltage electricity in the field winding. If the nail stands in the two magnetic poles, it means the wiring is correct.

Rewind the rotor winding. One end of the rotor winding is sawed off with a hand saw or turned off on a lathe, then placed on an electric furnace while rotating and baking, drying to 150-20 °C, the other end of the winding is clamped with needle-nose pliers, and the winding ring is pulled out one by one. Check the inter-chip, chip-to-chip insulation of the commutator segments. They should be intact. The slot insulation and embedded coil are placed after clearing. In order to ensure the symmetrical rotor balance and rotor balance, the winding should be performed in a certain order.

The outlet of the wire group and the welding of the commutator should be performed according to the recorded position. There are three methods of soldering welding: positive oblique two pieces, reverse oblique two pieces, and aligned commutator pieces. Among them, aligned commutator pieces are commonly used. The welding should be firm, and the thread head emerging from the groove should be cut off, the solder between the reversing plates should be scraped off, and finally the wire should be fastened in the new outlet area. After welding, the inter-turn short circuit test and the resistance test between the commutator segments are performed. After normal operation by electricity, dip paint treatment. During power-on commissioning, if the reverse rotation occurs, the positions of the two stator winding wire ends on the brush holder can be interchanged. After repair, check the insulation resistance and its value should be not less than IMn.