Каталог Iscar инструментальная оснастка 2022 - страница 7

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Balancing Elements

Balancing Definitions Balancing Coolent Chucks

Introduction Balancing is the process of equalizing the mass m distribution of a body so it rotates in its bearing without unbalanced centrifugal forces. Balancing causes reduced vibration, lower spindle strain and improved machining qualities, r and allows for higher cutting parameters. The measuring equipment available today enables unbalance to be reduced to low limits. However, it would

be uneconomical to exaggerate the quality requirements.Example 1
It has therefore become necessary to determine to whatU=2 g x mm can be treated as an unbalance mass
extent the unbalance should be reduced and whereof m=2 g in radial distance of r=1 mm or as a mass
the optimum economic and technical compromiseof m=0.1 g in radial distance of r=20 mm, etc.
on balance quality requirements would be struck.
Example 2
DefinitionThe residual unbalance is independent of the speed.
This value reflects the unbalance mass and its distance
G- Balance quality (mm/s)from the true center of mass. The residual unbalance
e- Specific unbalance (gxmm/Kg)value is measured on balancing machines.
Ω- Speed (rad/s)
N- Speed (rpm)4 U U
20 = 0.2g r = = m ∙ r = >m =
M- Mass of the body (kg)
m- Mass of the unbalance (g)G value reflects the balancing quality of a
r- Radius of the unbalance (mm)toolholder according to its rotational speed (N)
U- Residual unbalance (gxmm)
π ∙ N ∙ U = U ∙ N ∙ π G
e U= Ω ∙ e =
=M ∙ 30 M 30
M = > U = M ∙ e
Ω 2πNG ∙ 30 πN e
= 60π ∙ N = 30 =
OperationExample 3
Residual unbalance equals the tool’s mass (M)G value reflects the balancing quality of a toolholder
times its eccentricity (e). Eccentricity measures theaccording to its rotational speed (N).
extent to which the tool’s weight is off-center.
8 π U π G
It is defined as the distance from the tool’s center of theM = 30 ∙ 15, 000 ∙ 2, 000 ≈ 6.3 (mm/s) = 30 ∙ N ∙
rotation to its true center of mass.
If eccentricity is measured in microns and tool
mass is measured in kilograms, this unit yields8 U e
2 = 4 (g ∙ mm/kg) M = e = =
residual unbalance in gram-millimeters.
Any two sets of mass and eccentricity that yield theThe G value will change to G=2.5 mm/s when using the
same unbalance value will have the same effect onsame toolholder at a rotational speed
the tools, so long as the residual unbalance is in theN=6, 000 rpm and to G=1.0 mm/s at
same plane perpendicular to the rotation axis.N=2, 500 rpm.
U = r ∙ mBalance quality grades for various

groups of representative rotors:

  • General machine tool parts - G6.3

The residual unbalance is independent of the speed. General toolholders and machine drivers - G2.5 This value reflects the unbalance mass and its distance Grinding machine drivers - G1.0 from the true center of mass. The residual unbalance Spindles of precision grinders - G0.4 value is measured on balancing machines.