tire balance

The term refers to the balancing of reducing or eliminating an imbalance.

Everyone around a fixed axis rotating rigid body has an imbalance that vibrations ( oscillations), noise and increased wear at high speeds can even lead to destruction. When the manufacturing tolerances results in a large unbalance, a compensation must be made individually to the weight distribution in this body. The compensation can be positive or negative:

• In positive balance correction weights are applied, such as by welding, gluing or screwing of weights.
• When negative balance masses are removed, eg by drilling, grinding or milling.

A mixed form is the adjustment by screwing or unscrewing a screw.

Instead of changing the body, the rotation axis can be corrected such that the imbalance is minimized. This balancing is called balancing center.

The tolerances for balancing are standardized in DIN ISO 1940-1.

Balancing of vehicle wheels,

When balancing vehicle wheels a machine ( " Wheel Balancer " ) starts the wheel ( rim with tire ) in rotation ( rotation). The axis along which this occurs, is equipped with sensors. An electronic evaluation system is calculated from the measured values ​​of the forces at the axis of the unbalance. Balance weights are then secured to the rim in order to compensate the unbalance.

Differences are balancing weights after

• The application, that is, type of vehicle ( truck, car, motorcycle)
• Mounting (percussion weight, adhesive weight, plug Weight, clamping weight)
• Material and
• Operation (static or dynamic).

Following the decision of the European Commission of 27 June 2002 to end of life vehicles, the use of lead in balance weights was banned. Alternatively, since you used different materials, mainly zinc and steel; In addition tin, tungsten, and other plastics, which have a high density.

There are also dynamic balance weights. These have not been implemented, in particular due to limited functionality. It is an adhesive weight, which consists of a thermoplastic tube, which is filled with free-moving steel pellets.

Causes of the imbalance are uneven wear of tires and treads and uneven density distributions of the wheel body. Therefore, vehicle wheels need to be rebalanced after a tire change or other revision procedures.

The aim is not only to adjust the focus of the wheel to be balanced so that it falls on the axis of rotation, but also that the perpendicular to the rotational body wheel standing principal axis of inertia intersects not only with the rotation axis, but lies to her. Therefore often have to be attached to both sides of the rim counterweights.

Balancing determine through a rotational movement and a dynamic force measurement on the axis of rotation, the mass, the angle and the side of the rim, to be mounted on the counterweights.

Rotating Machinery and machine parts

Rotor or rotors and armatures of electric motors are often balanced by the laminated core of the finished rotor in the form of holes or notches areal removal is removed. Also, they are usually dynamically balanced, that is, it may need to be removed at both ends of the rotor material.

In order to be able to operate in any position, the moving coil must be balanced by moving coil instruments. You have this against the pointer displaceable or bendable counterweights. For a similar reason, the balance wheel of a clock must be carefully balanced. Otherwise, the clock errors of the alignment of the clock is dependent. Vibration and bearing wear play no role here.

The rotating masses of hurling washing machines, spin dryers and centrifuges for test tubes can not be balanced. Therefore, one outsourced their rotation axes move in a resilient and damping suspension to reduce the forces on the bearings and the environment. Modern washing machines often lead initially a spin at low speed and then try to spread by forward and rewind the laundry new, before the spin cycle starts with full speed. They have an acceleration sensor to the drum mounting, to monitor the unbalance.

Residual unbalances lead to a so-called critical speed at which the forces stimulate the oscillatory system as a whole ( spring-mass system consisting of rotor mass and wave or total mass and suspension / foundation ) to resonance. The critical speed is a danger of rapidly rotating machines (turbines, centrifuges, etc.); it is reduced by good balancing, by spring, damping suspension or by a particularly rapid passage through the critical speed during startup.