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Roll Grinding Measurement

RollCal™ and Rollcontrol™
Roll Measurement systems for perfect roll geometry.  Perform better in the SuperCalender with Accurate Roll Grinding through precise measurement of your Roll Profile.

Measurement for CNC Roll Grinding
Save Days of Grinding Time, Improve Finish and Crowns.

Roll Grinder Repair
Get that old grinder to perform like new with a grinder tune-up.

  • Align Beds
  • Repairs
  • Operator Training
  • Way & Bearing Scraping 

RollCal™ Classic - roll measurement device

RollCal™ Classic is a pioneer in the field of automated roll measurements. (Installations in 17 countries.) After being years on the market, it is still a competitive system for many roll measurement needs. The reports it generates are sufficient for basic requirements even today.

It is a simple and very reliable system with a high precision measurement capability. The system’s measurement electronics, software and Windows - user interface are regularly updated.
 

RollCal™ Classic can measure:

  • shape
  • crown and compound crown
  • roundness
  • concentricity
  • sag
  • roll alignment
  • grinder bed errors

(limitations apply on roundness measurements, see RollCal™2)

RollCal™ 2 – Roll Measuring Device

RollCal™ 2 is a fairly new system using the multipoint measurement principle enabling true measurement of roll roundness.

As paper machines´ production speeds have edged towards 2,000 m / min ( approx. 6,500 ft / min.) the roll geometry and overall condition deserve careful consideration.

RollCal™ 2 has been developed from RollCal™ but it provides additionally several new features.
The four-point measurement technique that RollCal™ 2 utilises True Out-of-Roundness™ measurement capability, which measuring the roll roundness always in the correct way. This is not the case with two-point roll measurement systems in spite of are they new, old or automated applications.

The optimised out-of-roundness of a workpiece and its impact on the paper making process have become critical factors especially in a certain roll positions. A good number of customers have been using RollCal™ 2 system for a few years and have proved that the improved measurement is needed ( See also RollControl™ i / 3D – Grinding ).

RollCal™ 2 can measure:

  • shape
  • crown and compound crown
  • true out-of-roundness
  • concentricity
  • sag
  • roll alignment
  • grinder bed errors

True Out-of-Roundness™

There are hardly ever perfectly round objects.
Out-of-roundness is a serious fault in paper machine rolls, causing vibration and significant periodic variation in paper quality. However, out-of-roundness is difficult to eliminate in grinding and until RollCal™ 2 was developed it was impossible to measure correctly.
Out-of-roundness can be presented as a spectrum or a combination of various waveforms of different amplitudes. This spectrum starts at 2nd lobe, which corresponds to an oval shape. 3rd lobe corresponding to a triangular shape, 4th lobe corresponding to a rectangular shape, etc.
Even waveforms (oval form, rectangular form etc.) can be measured with a 2 – sensor measurement system, but odd waveforms will be missed. The multipoint measurement technique (Four-point-measurement) is needed to detect also the odd waveforms.

The RollCal™ 2 System employs multi-point contact measurement using simultaneous displacement measurements, at multiple angular positions around the roll circle. The multi-point principle is the only practical method of measuring true out-of-roundness of large cylindrical rolls that must be measured while positioned in a machine tool.

RollCal™ 2 features an asymmetric sensor arrangement coupled with advanced signal processing. These features separate true out-of-roundness from the error motion of the axis of rotation without filtering out even or odd waveforms.

RollCal™ 2 is capable of separating systematic and repeating error motions as well as non-repeating random motions.

The RollCal™ 2 System utilizes the floating 4-point measurement principle using two measurement probes with sensors and two support probes. The sensor arrangement at the measurement frame is optimized to give the best detecting capability of the common waveforms. The new design of the sensor arrangement, carbon fibre composite measurement frames, software and electronics improve the measurement accuracy, make the system more versatile and offer extensive reporting that can be used for studies on the roll irregularities and their impact on the paper quality.

Reports

The new software provides very comprehensive reporting capabilities, for example, an out-of-roundness measurement consisting of several cross-sections can be reported as:

  • an ordinary graphic profile in a polar co-ordinate presentation
  • a diagram presenting the recorded waveforms with their amplitudes huom!
  • a colour-contoured sheet consisting of various cross sections, each colour tone representing certain amplitudes of deviation
  • a 3D-surface chart
  • as a 3D-cylinder, that can be rotated, with different colour tones indicate a certain amplitudes of deviation.

Similarly, measurement of diameter deviations can be reported as a graph.

The RollCal™ 3 - roll measuring device

The RollCal™ 3 is a brand new, automated four-point roll measurement system. The RollCal™ 3 continues to advance the highly successful RollCal™ Classic and RollCal™ 2 roll measurement systems applying up-to-date technology to the science of roll measurement.

The measurement system is based on the RollCal™ 2 measurement principle, but it uses four active sensors. The RollCal™ 3 software is similar to the advanced and proven RollCal™ 2 measurement software.

The major differences between these two systems are in construction and in operation. Whereas the operation of RollCal™ 2 can be considered semi-automatic, the movements for The RollCal™ 3 are automated. Additionally, the measurement capabilities of the new The RollCal™ 3 are even more versatile than RollCal 2’s.

The RollCal™ 3 continues to advance the highly successful RollCal™ Classic and RollCal™ 2 roll measurement systems applying up-to-date technology to the science of roll measurement.

True Out-of-Roundness™

Out-of-roundness can be presented as a spectrum or a combination of various waveforms of different amplitudes. This spectrum starts at 2nd lobe, which corresponds to an oval shape. 3rd lobe corresponding to a triangular shape, 4th lobe corresponding to a rectangular shape, etc. Even waveforms (oval form, rectangular form etc.) can be measured with a 2–sensor measurement system, but odd waveforms will be missed. The multipoint measurement technique (4-point measurement) is needed to detect also the odd waveforms of roundness. The The RollCal™ 3 System utilizes the 4-point measurement principle, with four active measurement sensors.
The sensor arrangement at the measurement frames is optimized to give the best detecting capability for the most common waveforms (undulations per round).

The The RollCal™ 3 System is capable of measuring both even and odd waveforms in the out-of-roundness measurement.
The traditional 2-point measurement principle misses the odd waveforms and therefore very seldom gives a true out-of-roundness measurement. The new design of the sensor arrangement, the use of very high quality components, software and electronics improve the measurement accuracy, make the system more versatile and offer extensive reporting that can be used for studies on roll irregularities and their impact on the paper quality.

RollCal™ 3 can measure

  • diameter deviations (shape)
  • crown and compound crown
  • true out-of-roundness
  • concentricity
  • roll diameter
  • movement of center axis
  • roll alignment
  • grinder bed errors

Roll diameter range for measurements: 200–2000 mm (7.87–78.7”)
Measurement accuracy: 1 µm or better (0.00004 inches)
Repeatability: 3 µm (0.00012 inches)

Reports

The software provides very comprehensive reporting capabilities, for example, an out-of-roundness measurement consisting of several cross-sections can be reported as:

  • an ordinary graphic profile in a polar co-ordinate presentation
  • a diagram presenting the recorded waveforms with their amplitudes
  • a colour-contoured sheet consisting of various cross sections, each colour tone representing certain amplitudes of deviation
  • a 3D-surface chart
  • as a 3D-cylinder, that can be rotated, with different colour tones indicate a certain amplitudes of deviation.

Similarly, measurement of diameter deviations can be reported as a graph.

RollControl™ i - The Intelligent Grinding Control System

RollControl™ i is an integrated computer numeric control (CNC) solution specifically designed and developed for roll grinding machines. It can be installed on practically any roll grinder or lathe. The system is flexible and can be tailored to meet the demands of each grinder applications.

RollControl™ i automates the control of the machine’s critical axes, monitors machine functions and provides on-line information about the grinding process through its easy-to-use graphic user interface.

The heart of the RollControl™ i system is a sophisticated CNC computer i.e. Multi Axis Controller. This controller, combined with RollCal’s (RollCal™ 2 or RollCal™ 3) computing software allows soft and hard rolls to be ground with precision to a desired profile, finish, or correct roll geometry. These two systems work synergistically to improve roll quality, reduce grinding times, compensate for roll roundness and concentricity, reduce grinder maintenance downtime, and improve paper quality.

Accurate roll geometry has a profound impact on paper quality. Consequently, RollControl™i features two main grinding modes. Contour Grinding™ is especially designed for grinding “soft” rolls; rubber covered suction rolls for example. In Contour Grinding mode errors in roll alignment, taper, bed deviations and grindstone wear are compensated for. RollControl’s Shape Error Compensation greatly improves the grinding quality over that available with conventional Contour Grinding.

The unique SuperGrind™ is designed for grinding “hard” rolls such as chilled iron and its unique capabilities result in a superb finish with a very high control accuracy. One of the SuperGrind’s powerful features is its ability to reduce the roll’s roundness and concentricity errors automatically during the grinding process. Error sources deriving from the workpiece or grinder are compensated for.

3D Dynamic Grinding™ - compensates roll’s shape errors that derive from e.g. worn bearings or inconsistent roll frame structure. All grinding modes represent very advanced and unique computing for target profiles based on the different measurements and entered parameters. 3D Dynamic Grinding™ advanced feature is needed to optimise the out-of-roundness profile of the rolls. Especially the improvements in roundness accuracy with covered rolls is significant.

The RollCal™ 2 or RollCal™ 3 systems using the four-point measurement technique that enables the true out-of-roundness measurements is needed for delivering a 3D-surface map or the roll geometry for the CNC.

In most cases the needed roll measurements are performed once the roll is on a grinder. The measured data is transmitted to the CNC for 3D-grinding. The needed roll measurements for 3D-grinding can also be made on a roll balancing machine. These “dynamic” measurements are required for optimizing a roll roundness to a certain production speed.

The experiences with the 3D-grinding have been very good. In some cases even the production or runnability problems have been solved with 3D-grinding providing optimised roll accuracy.

All grinding modes represent very advanced and unique computing for target profiles based on the different measurements, entered parameters and continuous process monitoring.

SagComp™

When roll is stationary - and supported only at the ends - it gradually starts to bend due to its own weight. When rotation starts the roll begins to straight out. First pretty quickly and then slower. Before grinding can be started the roll needs to be rotated from hours up to a day to avoid unnecessary grinding.

However, using roll grinder as a roll rotation device is ineffective and on the other hand starting to grind ”too early” leads to extended grinding times and removal of roll cover material.

To RollControl™ i - system a compensation for roll’s plastic deflection can be added. The wheel is made to follow a generated target circle where only roundness error and irregularities will be ground off.

The control of the compensation is adaptive i.e. it automatically adjusts to changes in roll’s deflection.

RollControl™i can be added with several optional control or monitoring functions.

In addition to the main grinding modes RollControl™ i can be used for taper grinding, wheel dressing and groove cutting.

We can deliver as well RollGroove™ Cutting Tool and RollBelt™ devices.

RollControl™ Si – Integrated real-time roll measurement and CNC solution for grinders

RollControl™ Si is an integrated automation solution for roll grinders used in aluminium- and steel industries. The system is designed for the users needing high performance, top grinding quality, ease of use and high automation level for their roll grinding operation.
RollControl™ Si system incorporates a fully automated roll measurement system, CNC control, electrical devices, motors and other essential devices such as any accessories, cabling and mechanical components required when fitting the system onto a grinder.

Roll measurement system

The roll measurement system is fully automated. All its movements are generated with electrically controlled devices. The control system drives the measurement beam automatically from the “home position” to the “work position”, starts and stops the measurement passes and controls the arm positions during the measurement.
The system measures the diameter of the work piece with two sensors. The work piece normally rotates during the measurement, but measurement can also be performed on a stationary roll.

Eddy current – sensor is available as an option for the system. This device will detect the damages, bruises and cracks of the work piece.

The temperature measurement gauge can also be supplied as an option. This device and its software will detect and generate a temperature profile of the work piece surface.

Grinding

A graphical display is interfaced to the RollControl™ Si system for the operators to monitor the machine functions in real-time. The target and measured profiles are continuously updated and displayed on the screen. Additionally the positions of all machine axes are displayed in numerical format as well as status of the machine and possible messages or alarms.
The control system communicates transparently with the roll measurement system and the roll database.
In cases where automatic mode operation has been selected, the control drives the measurement system and starts measurement passes and analysis processes independently without operator intervention.

The control system will be utilising the programs and working cycles that are agreed to be delivered for the customer. Further, the system features a possibility for the customer to amend and add programs. In normal use the operator selects the roll from the roll menu and a suitable grinding recipe for the roll and activates the process by pushing one button on the control panel. The CNC starts the grinding process and continues until the entered quality requirements are obtained. The requirements can be the following: target diameter, minimum diameter, shape tolerance and minimum amount for rough grinding.

Remote control and monitoring

A remote control- and monitoring feature can be added to the RollControl™ Si –system as an option.
 

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