Novel servo-feed-drive model considering cutting force and structural effects in milling to predict servo dynamic behaviors

This paper proposes an Optimized Feed Scheduling Strategy (OFSS). This strategy integrates the feed drive dynamics with the minimum-time trajectory planing to achieve the desired feed rate at the appropriate tool position along specified tool path. It optimizes the use of the feed drive capabilities and provides good tracking of the cutting geometry variations. The feed scheduling is applied to maintain near-constant cutting force magnitude. An integrated geometric and mechanistic force model is used to estimate the in-cut geometry and the cutting force. A methodology based on time series modeling and analysis is proposed to identify the low frequency feed drive dynamics. The resulting model is applied as an acceleration/deceleration processor (Acc/Dec) to relate the actual feed rate to the commanded feed rate specified in the G-Code file. The effectiveness of the OFSS is analyzed using ball end milling operations. Its performance in terms of productivity and machining safety is assessed based on comparison with other feed scheduling techniques where the trajectory planing does not consider the feed drive dynamics.

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Nonlinear Dynamic Behaviors of Rotor Systems for Ball End Milling

Volume 5: Structures and Dynamics, Parts A and B ◽

10.1115/gt2008-51461 ◽

2008 ◽

Author(s):

Ting-Nung Shiau ◽

Kuan-Hung Chen ◽

K. H. Huang

Keyword(s):

Nonlinear System ◽

Linear System ◽

Cutting Force ◽

Nonlinear Dynamic ◽

End Milling ◽

Depth Of Cut ◽

Dynamic Behaviors ◽

Ball End Milling ◽

Critical Speeds ◽

Rotor Systems

The nonlinear dynamic behaviors of rotor-bearing system for ball end milling are studied in this paper. The rotor system is supported by bearings with nonlinear spring effects. The nonlinear cutting force can be calculated by using the Tlusty proposed 3/4 rule for chip thickness. The effects of design parameters on system dynamic behaviors including critical speeds and stability under the dynamic cutting forces are numerically investigated in the time domain. For linear system case or the nonlinear system with small depth-of-cut or feed per tooth under linear cutting force, the results show that the critical speeds of system are proportional to the corresponding system natural frequencies, but inversely to the cycle number of tool vibration multiplying by the number of flutes during the cutting time from one flute to another. With large depth-of-cut or feed per tooth, the differences of the critical speeds become larger between linear and nonlinear rotor systems and so are the dynamic responses at critical speeds milling. The critical speed under nonlinear cutting force milling is found to be always higher than that under linear cutting force. Furthermore, the chatter stability lobes are studied for various cutting conditions. The intervals between critical speeds increase gradually, and the axial depths of cut of nonlinear system for stability are lower than those of linear system.

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Prediction of Cutting Forces and Tool Breakage in Milling from Feed Drive Current Measurements

Journal of Engineering for Industry ◽

10.1115/1.2900688 ◽

1992 ◽

Vol 114 (4) ◽

pp. 386-392 ◽

Cited By ~ 160

Author(s):

Y. Altintas

Keyword(s):

Cutting Force ◽

Force Measurement ◽

Milling Process ◽

Tool Breakage ◽

Tool Failure ◽

Feed Drive ◽

Drive Control ◽

Failure Event ◽

Vertical Milling Machine ◽

Milling Forces

This paper describes the use of current drawn by feed drive motors for milling process monitoring. A model of a vertical milling machine feed drive control system is used to analyze cutting force measurements from the drive motors. The current and voltage limits in the amplifier, and the friction in the feed drive assembly are included in the analysis. The viability of using armature current as a cutting force measurement sensor is discussed. The pulsating milling forces are predicted from the current measurements at tooth passing frequencies which are within the bandwidth of the servo. It is shown that tool failure in milling can be detected within one spindle revolution by adaptively filtering the average current signals at tooth passing periods. The residual terms of a first order auto-regressive time series filter is found to be sensitive to the tool failure event. The tool breakage algorithm is independent of cutting conditions and the friction in the drive system.

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A sample construction method in kinematics characteristics domain to identify the feed drive model

Precision Engineering ◽

10.1016/j.precisioneng.2020.11.006 ◽

2021 ◽

Vol 68 ◽

pp. 82-96

Author(s):

Jing Zhang ◽

Jiexiong Ding ◽

Naohiko Sugita ◽

Toru Kizaki ◽

Qingzhao Li ◽

...

Keyword(s):

Construction Method ◽

Feed Drive ◽

Drive Model

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the effects of resonance with Jupiter in the system of short-period comets

International Astronomical Union Colloquium ◽

10.1017/s0252921100033959 ◽

1974 ◽

Vol 22 ◽

pp. 193-203

Author(s):

L̆ubor Kresák

Keyword(s):

Structural Effects ◽

Order Resonance ◽

Mean Motion ◽

Short Period ◽

The Mean ◽

Compound Effect ◽

Low Order

AbstractStructural effects of the resonance with the mean motion of Jupiter on the system of short-period comets are discussed. The distribution of mean motions, determined from sets of consecutive perihelion passages of all known periodic comets, reveals a number of gaps associated with low-order resonance; most pronounced are those corresponding to the simplest commensurabilities of 5/2, 2/1, 5/3, 3/2, 1/1 and 1/2. The formation of the gaps is explained by a compound effect of five possible types of behaviour of the comets set into an approximate resonance, ranging from quick passages through the gap to temporary librations avoiding closer approaches to Jupiter. In addition to the comets of almost asteroidal appearance, librating with small amplitudes around the lower resonance ratios (Marsden, 1970b), there is an interesting group of faint diffuse comets librating in characteristic periods of about 200 years, with large amplitudes of about±8% in μ and almost±180° in σ, around the 2/1 resonance gap. This transient type of motion appears to be nearly as frequent as a circulating motion with period of revolution of less than one half that of Jupiter. The temporary members of this group are characteristic not only by their appearance but also by rather peculiar discovery conditions.

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