Каталог Iscar инструментальная оснастка 2022 - страница 7

TOOLING SYSTEMS INTRODUCTION 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 what U=2 g x mm can be treated as an unbalance mass extent the unbalance should be reduced and where of m=2 g in radial distance of r=1 mm or as a mass the optimum economic and technical compromise of m=0.1 g in radial distance of r=20 mm, etc. on balance quality requirements would be struck. Example 2 Definition The 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)M-Mass of the body (kg) U = m ∙ r = >m = Ur = 420 = 0.2g 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) e= UM =>U=M∙e G =Ω∙e= π∙N30 ∙ UM = U∙N∙πM ∙ 30 Ω= 2πN60 = πN30 e= G ∙ 30π∙N Operation Example 3 Residual unbalance equals the tool’s mass (M) G value reflects the balancing quality of a toolholder times its eccentricity (e). Eccentricity measures the according to its rotational speed (N). extent to which the tool’s weight is off-center. It is defined as the distance from the tool’s center of the G = π30 ∙ N ∙ U π 8M = 30 ∙ 15, 000 ∙ 2, 000 ≈ 6.3 (mm/s) rotation to its true center of mass. If eccentricity is measured in microns and tool mass is measured in kilograms, this unit yieldsresidual unbalance in gram-millimeters.e=UM=e=82= 4 (g ∙ mm/kg) Any two sets of mass and eccentricity that yield the The G value will change to G=2.5 mm/s when using the same unbalance value will have the same effect on same toolholder at a rotational speed the tools, so long as the residual unbalance is in the N=6, 000 rpm and to G=1.0 mm/s at same plane perpendicular to the rotation axis. N=2, 500 rpm. Balance quality grades for various U=r∙m 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. 555