The wholesale production of manual grinding machines was started in the USSR in 1940. The name “Bulgarian” received this adaptation due to the fact that it was first produced in the small Bulgarian town of Lovech, which had a patent for this invention.
The device is Bulgarian.
Today, no production can do without this tool. However, any tool breaks once, but many parts can be repaired in the living conditions.
The electric part often burns. The reason for this may be:
- strong heat from high overloads;
- power surge;
- water that gets on conductive surfaces;
- sharply pulled out of the socket;
- hit the switch and so on.
The most common malfunction that you can try to repair is the breakage of the stator windings. This is mainly due to large overloads. Rewinding the stator of the grinder with your own hands today is quite possible. However, such work requires some experience and relevant knowledge.
Most often the electric motor fails for a number of characteristic reasons:
- winding is broken;
- the magnetic circuit is torn;
- disrupted the work of the anchor collector.
Signs of a broken stator
Schematic diagram of the regulator of revolutions of the grinder.
When the voltage rises, the strength of the spark increases in steps. And most often only one brush is exposed to this phenomenon. As a result, the insulation of the wire wound on the stator coil breaks through.
When the collector is highly sparking, this means that the anchor has poor balancing. When checking the collector increase the voltage, the sound of the engine must slowly and smoothly increase, while there should be no vibration.
With the appearance of resonance, we can talk about poorly made balancing. Requires repair of an electric motor.Back to table of contents
Connection diagram of the collector engine.
It has three main nodes:
The armature is a rotating part having windings to create the required torque, which is transmitted to the gearbox of the electric motor. The same winding has a stator, which is divided into several parts. An electric current comes to the winding through a carbon brush and enters the anchor. Then the current comes to the next brush and so on, until all sectors of the stator are involved.
An anchor is installed in this stator. This element of the design of the grinder is considered the most difficult, since almost all windings are pressed in it.
The stator of the electric motor has the same appearance. Characteristic differences are:
- dimensions of the magnetic circuit;
- wire speed;
- wire section.
When electricity runs through the armature windings, a magnetic field arises that constantly interacts with the same stator field. This interaction starts the motor. Sometimes permanent magnets are part of the stator. For example, such parts have a motor wiper motor. Each collector motor is able to operate from any kind of voltage. When changing its value, it is possible to adjust the desired number of revolutions.
Characteristic malfunctions of the stator are:
- winding break;
- interturn short circuit;
- burnt winding;
- breakdown of the insulating surface.
When the chain is working normally, the anchor starts to rotate and with the help of gears the disk is set in motion.
Scheme check collector engine.
The gearbox maintains certain speed and speed. Repair grinder is quite available in the domestic environment. It is only necessary to pre-disassemble the device.
In order to move the cover, you need to unscrew the screw that secures the plastic plate. All parts will be visible, except for the gearbox, which hides the metal cap. It does not allow the gearbox to be very hot. To remove the gearbox, unscrew the four screws. Thus all mechanical details of the Bulgarian will be exposed.
When the device is plugged into the socket and the disk accelerates at high speeds, this means that the stator winding has a winding short circuit. The stator requires repair, most often it needs rewinding.
It seems that stator rewinding is a job of increased complexity. Argued that to carry out such work at home is almost impossible. After all, sometimes even experienced motor wrapers refuse such work. However, having the relevant experience and certain technical knowledge, an ordinary three-phase stator can be repaired in a few hours with all the preparatory work.
Before starting repair and rewinding, the stator must be cleaned of dirt and removed from the grooves of the old winding. This work is done with the help of steel brushes. In addition, damaged insulation is removed. To facilitate cleaning from isolation, the stator is dipped into heated transformer oil, which softens the remaining insulation.Back to table of contents
What may be needed to repair the stator?
Tools required for work: round pliers, ruler, caliper, pliers, electric drill, steel brush, megger.
For the work of the master will need:
- round nose pliers;
- steel hammer;
- wooden hammer;
- steel brush;
- electric drill;
After cleaning the stator from dirt, it is necessary to carry out the following sequence of actions:
- metal bags are checked;
- burrs are removed;
- the studs holding the core are tightened;
- insulation resistance is determined;
- push-in washers, edges of the core, varnished;
- Isolation of the grooves is done.
Repair of the electric motor stator
Reversible rotation of the collector engine.
First, the front windings are cut off. Then a new winding is made. It is made on the template, fixed on the axis, which holds two large plates. It is very important to get the right amount of turns in such work. Wire of a certain diameter should have a maximum seal. Two coils are inserted into the stator body. Conclusions are drawn from the magnet wire, which are insulated with flexible plastic tubing and cambric.
Before starting the laying of the winding, according to the technological process, the symmetry of the slot boxes is checked. If they do not cover the winding, temporary liners are installed to prevent damage to them when coil wires are laid.
The coil, which will need to be laid, is mounted directly above the surface of the groove below the bore. By means of a special plate installation of coil conductors is carried out.
To avoid crossing the wires, which are located in the groove, they are laid in exactly the same sequence as the winding on the template. The location of the conductors must be strictly parallel.
During the next operation, the stator housing is rotated one division. Is laying in the groove of the other coils from the initial coil group. After that, install interlayer gaskets into the grooves. The pins of the coil group are screwed to the outer contour of the coils with a string. These ends should be parallel to the coil terminals. A similar method is used to assemble the bottom side of the coils of the next coil group. This operation continues until all the grooves of the coils that are included in this step are completely filled.
After the end of the winding, the stator coils are spooled. The sleeves must be of a certain size, depending on the dimensions of the stator. The thickness of the material for the liner is 0.2 mm. The length of the sleeve must exceed the size of the stator. Almost always the excess is 1.5 mm.
The material of the liner is a special electrical cardboard. A heat-resistant film is wound on top of it. The resulting design wraps sticky tape. Then, spool coils are mounted in the stator grooves, and the free movement of the armature is checked.
Fully formed coil tied with a keeper tape, then coated with varnish. The completion of all work is complete drying, after which the stator will be fully operational.