Contents
BALANCING OF ROTATIONAL BODIES
- Shafts, spindles, drums, wheels, rotors, crankshafts -
Definitions
By balancing we mean checking and correcting the mass distribution of
rotationally symmetrical bodies. The best-known example is the balancing of car
tires. The assembly of the tire with the rim is checked for concentricity using
rotation. The correction is carried out using adhesive weights until the center
of the masses is on the axis of rotation. This is a dynamic balancing process.
The terms static balancing and dynamic balancing are explained by the fact
that the static unbalance can already be recognized in idle stationary
condition, while the dynamic unbalance only becomes apparent during ongoing
operation (rotation). For static balancing, balancing in one reference plane is
sufficient. Dynamic balancing takes place in two levels, which ideally should
be as far apart as possible.
In mechanical engineering, the masses can also be balanced by drilling
holes instead of adhesive weights. Holes can also be filled again to
compensate, for example by screwing. Alternatively, removing material by
turning or grinding is also conceivable.
Advantages or requirement of balancing
Balanced shafts or drums reduce or avoid unwanted reaction forces, thereby
minimizing noise and wear. Balanced shafts increase the precision of work
spindles and shafts during operation. Resonances can even lead to the
destruction of rotationally symmetrical components, especially when critical
speeds are reached.
Balanced components have the advantage that, for example, higher speeds can
be achieved. Balanced work spindles increase the precision of the workpiece
while simultaneously increasing tool life.
Dynamic balancing achieves better balancing results compared to static
balancing.
Application examples in mechanical engineering
Typical
application examples for balancing services include spindle shafts of turning,
milling and grinding machines as well as rotors, armature shafts and other
types of spindles.
Individual
workpieces (e.g. correction of roundness or concentricity errors) but also
assemblies can be balanced. An example is the tool in the tool holder (e.g.
collet) installed in a work spindle.
For
disk-shaped parts, a static balancing procedure is often sufficient.
Balancing machine technology
Balancing machines are available in horizontal and vertical versions. To
determine the imbalance, the balancing machines determine the difference
between the mass axis and the running axis. The accuracy is in the single-digit
thousandth range.
Norms also set standards in the area of balancing. For example, the
standard states DIN ISO 16084 specifies the balancing of rotating tools and
tool systems. The permissible residual unbalance is defined in the unit gmm.
Another standard is DIN ISO 21940-1 with the topics of mechanical
vibrations and balancing classes when balancing rotors.
Modern balancing machines with precise electronics usually easily exceed
the accuracy of standards.
Balancing
machines on tramao
On tramao,
balancing machines have their own category. You can find these in the metal
working machines section in the subcategory fine machining – balancing
machines.
Main
manufacturers of balancing machines
If you decide to buy a new or used balancing machine, you will find a large
selection of well-known manufacturers on tramao such as CIMAT, Schenck, Hofmann
and Reutlinger.