ShakesBear

Spindle and Dynamics Analyzer Systems

Spindle and Dynamics Analyzing Systems with Nanometer Resolution and for Speeds of up to 100.000 rpm

SEA

Where other spindle manufacturers can rely on suppliers, Levicron is forced to develop key spindle components to achieve and guarantee the quality and performance of their spindle products. As such features are not commercially available, their development often leads to new products. It also applies to the technology to analyze, test, and verify the properties and quality of spindles that Levicron has been developing since the beginning and are unique regarding resolution, sampling rate, and use.
With our spindle analyzing and testing systems „ShakesBear, Hamlet“ and „ShakesBear, Othello, “ Levicron can now provide all-in-one spindle analysis and testing systems for up to 100.000 rpm on a nanometer level.
Measurements of dynamic tool run-out, spindle errors (SEA), vibrations with speed, and spindle/system resonance maps are stored as reports and raw data in a local or server-based spindle/machine database that can be recalled at any time required.

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Demo Software available

Although there won’t be any actual function without the hardware, we can supply you with a demo of our ShakesBear software. With the demo, you can feel how to use the software, how a SEA is done, and how the machine/ spindle database works. The database features are based on Levicron products but can easily be customized to your needs. Please ask us if we should send you a download link of the ShakesBear Software demo (*.iso file).

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ShakesBear, Hamlet

Our all-in-one spindle analyzing system „ShakesBear, Hamlet“ has specifically been developed to acquire spindle errors (error-motion) in radial and axial directions at a nanometer level up to 100,000 rpm. The integrated direct error-separation of spindle synchronous and artifact shape errors allows measurement in a single test setup without changing the system or the spindle. The mobile rack includes the amplifiers, filters, connectors for the sensors, and a PC connection.

ShakesBear, Othello

The all-in-one spindle testing system „ShakesBear, Othello“ targets machine and spindle dynamics like dynamic tool run-out and vibrations, thermal shaft growth, and spindle/ machine resonance maps. Here the spindle can be used as an excitation to the machining system where a waterfall FFT with spindle speed is generated to identify system resonances. With an optional, integrated PC and a touch screen, this system allows quick and mobile use at the customer site or in your test field. Also, for the Othello system, all amplifiers, filters and connectors are part of a mobile rack to which the sensors can be connected to.

Modules

The most significant deviation of the shaft spinning axis in radial or axial direction from an ideal axis is defined as Error-Motion. In this case, the ideal spinning axis has the lowest average overall measurements.

Spindle errors can be distinguished between synchronous and asynchronous where

  • Synchronous Errors repeat with every rotation at the same shaft angular position and
  • Asynchronous Errors are not repeatable between shaft rotations.

The Run-Out (fundamental) is a perfect spindle error polar plot circle and represents an off-centered tool. Thus run-out is not a spindle but a tool error.

Therefore the spindle error (Error-Motion) in the radial direction is defined as:

∑Sync.Errors + ∑Async.Errors – Fund. (run-out)

 

Direct (auto) error-separation:

Any measurement of radial spindle errors is taken against the spindle shaft or any object attached to it, preferably perpendicular to the equator of a precisely lapped sphere. However, any roundness error of the equator repeats with the shaft rotations and would be detected as a synchronous spindle error. Although there are methods to separate the target shape error from the spindle synchronous errors, those require two measurements and a change in set up in between two measures and are significantly error-prone.

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By using at least three radially arranged distance sensors around the spinning axis, it is possible to separate spindle synchronous errors from the target shape errors by solving a complex transposed equation system before converting the signal back into the time domain. Levicron has included the direct error separation into their SEA treatment so that synchronous, asynchronous, and target shape errors can be measured and separated in one setup and a single measurement.

SEA

The included low-noise capacitive distance sensor with 2 nm resolution and 100 kHz sampling rate allows a sound measurement of the tool run-out at spindle speeds of up to 100,000 rpm. At the same time, a piezo-mass accelerometer detects spindle vibrations. An external trigger or the laser-tacho gives the spindle speed to create a continuous dynamic run-out, and spindle vibrations chart over speed.

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Due to its high resolution and sampling rate, the capacitive distance sensor is capable of detecting the amplitude of the fundamental (spinning frequency) and any frequencies up to 4 kHz. As vibrations can be measured as a change in the distance, the capacitive gauge can be used to create an FFT spectrum at discrete spindle speeds. Changing the speed from stand-still to top speed, or vice-versa allows the creation of a continuous Waterfall-FFT chart where the single FFT charts are lined up and arranged with speed. The resonance speed map feature represents a 2.5-D Waterfall-FFT (looking top-down on a 3-D Waterfall diagram) where dark areas mean higher and light areas lower values. It allows the identification of spindle and system natural frequencies and resonances at which the fundamental (spindle frequency) crosses a natural system frequency.

When the capacitive gauge is used as the source, spindle frequencies are naturally measured dominantly. Using the included accelerometer instead gives natural frequencies of the entire system, including pumps, hydraulics, and chillers e.g. Placing the accelerometer anywhere in the system can thus be used as a tool to identify natural system frequencies with the spindle as a vibration source

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When used axially against the spindle shaft, the capacitive gauge measures the thermal shaft growth with time. Along with an optional temperature sensor, which can be placed on any part of the machining system, the thermal shaft growth, temperature and spindle speed can be measured with time where the spindle speed can be detected using either an external trigger or the included laser-tacho.

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Using the included accelerometers or cap gauges, the FFT module offers an easy-to-use tool to measure and display the vibration amplitudes of the frequency spectrum and thus identify spindle or system natural frequencies while running the spindle or as a response to an impulse (Dirac Impulse). A Dirac-Impulse, also known as step response, can be re-assembled as the sum of all harmonics within the frequency spectrum. It means that a gentle hit at the spindle nose or anything in the system would excite all frequencies; thus, the spindle or the entire system would respond with larger amplitudes at its natural frequencies.

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To set up the stand-off of the included cap gauges and to radially align the spindle artifact, the cap gauges measure against the included 4-channel, digital drag-pointer dial gauge can be used.
It can also be used to measure the static run-out of the artifact when turning the spindle by hand or at low speeds.

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For an ISO certification in particular, but also for tracking the quality of the spindle products for internal use or customers, all measurements and results must be recorded and stored electronically. For this, our ShakesBear Software is designed to work with server systems. It is also based on a spindle or machine tool database in which all reports and rat data are stored . Whether connected to a server or working locally, the database module generates a folder structure for each serial number in which all reports and raw data are stored that can be recalled at any time

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