The angle grinder is used for cleaning, grinding and polishing various surfaces, edges and welds. They are also very effective for cutting various materials and products made of brick, stone, concrete, metal. Due to the wide development of diamond tools, the angle grinder has become a universal cutting machine, which is difficult to do without in the country.
Wear gloves when working with the angle grinder
The principle of operation of the angle grinder is visible from the first glance at it:
- The current-conducting cable of the motor, and the control unit ensures the rotation of the motor rotor;
- Its shaft is equipped with a fan and a gear gear, which is engaged with the driven gear mounted on the drive spindle. It is the latter that makes the working tool rotate-a cutting disc or a grinding stone.
The main parameter of the angle grinder is the outer diameter of the grinding or cutting wheel. Based on this, they can be divided into one-handed and two-handed:
- single-handed – without the main handle with a circle diameter of 100, 115, 125 mm (3.9, 4.5, 4.9 inches) and a weight of up to 2.5 kg (5.5 lb);
- two-handed – with the back of the main handle and an additional handle; the diameter of the circle in this case is 125-230 mm (4.9-9 inches), the weight of the machine is 2.5-6 kg (5.5-13.2 lb).
Discs of different diameters have different speed limits-this information is always indicated on the disc label.
The operating modes and conditions of the angle grinder are a serious test for the operation of its adjustable electric drive. It is supplied in a dust-proof design that prevents dust from getting on the motor windings and bearings. Such drives allow you to:
- smooth increase in the number of revolutions of the spindle to the maximum speed, allowing grinding and cutting at speeds as close as possible to the permissible ones;
- automatic stabilization of the speed limit when changing in the process, the force on the device.
This, firstly, increases the degree of use of engine power. And secondly, it reduces the starting current by 2-3 times, allowing the electric drive to operate with a power of up to 2,500 W in electrical networks with 16 A fuses.
Fit of silicate material
The Achilles ‘ heel of the used collector electric motors is their current-collecting device, which is made in the form of a contact pair “collector-brush”. The leading manufacturers of the angle grinder guarantee the reliability of the current collector even in grinding machines that are characterized by increased motor power, high angular velocity, and significant mechanical and thermal loads. However, the service life of carbon brushes is about 200 hours or more. Some models have self-locking brush systems that protect the engine from damage.
A characteristic feature of the working process is the high speed of the cutting wheel. It provides a tool speed sufficient for cutting metals. However, even minor irregularities in the structure of the disc material or uneven wear of the working surface lead to some imbalance, which causes the machine to vibrate. This reduces the durability of the bearings, increases operator fatigue. To eliminate this phenomenon, an anti-vibration device is used in the form of a set of balls installed in the annular groove. They automatically eliminate the imbalance.
Another logical way to deal with vibration is the insulation of the handles. They are installed using special elastic damping devices that dampen vibrations that reach the operator’s hands. In some cases, the handles themselves or their surface are made of materials with good damping properties. The combination of these methods allows you to reduce the level of vibration (acceleration) below 2.5 m / S2, which, in accordance with international ISO standards, does not require restrictions on the duration of work with the machine.
When working with the angle grinder, remove the flammable materials lying next to it
For the convenience of operating the machine, it is often possible to install the handles in several positions. To allow grinding in hard-to-reach places, the body of the working head is designed in the form of a “duck nose”, but sometimes in a rotating position with several positions. The protective housing-an integral part of angle grinders-protects the operator from mechanical damage.
In the second part of the article, we will look at the algorithm for choosing a specific model, the types of disks and working stones, as well as talk about safety in the operation of angle grinders and the prospects for the development of their designs.