“Our largest machine used to accommodate parts up to 600 mm diameter, but the VTG4000 can handle diameters in excess of 4000 mm, the size of the largest wind turbine bearings. This is hard turning and grinding which can be very demanding, and the positioning accuracy is very important, with a direct effect on the quality of the finished bearings. A standard size machine, using ballscrews on the axes, will manage to maintain a 3 µm form deviation, yet despite the considerable difference in relative size, the VTG4000 has been proven to achieve an exceptional form deviation of less than 1 µm, with feed resolution in 0.1 µm steps,” said Eive Johansson, Lidköping’s VTG Chief Designer.

“At the heart of a Lidköping machine are the linear slides. The combination of hydrostatic guideways, air seals and linear motors create a stiff, accurate and maintenance-free system. To achieve dynamic stiffness we need high gain and the gain is linked to the quality of the encoder scales. It also makes a big difference that the angle encoders have the scale integrated directly onto the ring,” he added.

Mr. Johansson first saw the Renishaw SiGNUM encoders during the EMO 2007 exhibition in Hannover, and then followed a period of rigorous testing by the company. As he explained: “The choice of Renishaw was easy; we compared different scales assembled on our reference slide and bought the one with the best performance. It was important that the linear encoders could be supplied in a continuous length of at least 4.5 m and SiGNUM is the easiest way to achieve this. The Renishaw encoders also give more resistance to dirt. We have now fitted Renishaw encoders to all four linear slides and as expected, we have had no problems!”

“The rotary table has the same design principle, with hydrostatic radial and axial bearings, air seals and torque motors for the drive. The same analysis was done, and the Renishaw SiGNUM angle encoders were chosen,” he added.

The Renishaw encoders have an integral patented set-up LED that speeds installation and eliminates the need for separate set-up equipment/complex external, or oscilloscopes.

“One of the best features of the Renishaw encoders is how easy they are to set-up,” Mr. Johansson said. “With the scale attached and the readhead approximately located the indicator lights make it very easy to see how well the two elements are aligned and then make the final adjustments.”

The FASTRACK system consists of two miniature guide rails that secure low-profile scales (8 x 0.2 mm cross-section) while allowing them to freely expand at their own thermal expansion rate with almost zero hysteresis. The scale can be installed, removed and reinstalled as many times as required, and damaged scales can be pulled out of the guide rails and quickly replaced, even where access is limited, reducing machine downtime.

FASTRACK is available on reels for cut-to-length flexibility at the point of installation, allowing machine builders to minimize stock and lead-times. Generous tolerance makes measuring and cutting quick and easy. Easily installed, the self-adhesive guide rails feature integral pre-aligned sacrificial spacers which are removed after the rails are fitted to the axis. The scale is then fed in from either end and locked to the substrate at a single datum point anywhere along the axis using cyanoacrylate glue or a clamp.

Part of a modular solution, FASTRACK can be used with either the RTLC stainless steel incremental scale and super-compact TONiC readhead, or Renishaw’s new RESOLUTE linear absolute encoder and RTLA absolute scale. The encoders in both set-ups feature advanced optoelectronics with resolutions to 1 nm, low sub-divisional error (SDE) and very low jitter for smooth velocity control and rock-solid positional stability. For TONiC RTLC incremental scale installations, limit magnets and a reference mark selector are fitted to the FASTRACK and secured with a bolted clamp rather than using glue. The RTLC scale features multiple INTRAC reference marks at regular spacing.

The FASTRACK system is backed by Renishaw’s global sales and support network and, like the TONiC and RESOLUTE encoder systems, it is compliant with the WEEE and RoHS environmental standards.

Renishaw
www.renishaw.com/encoders

The linear encoders are used with magnetic bands that are attached to the mounting surface and protected by a stainless-steel cover. The encoder’s resolution is up to 5 µm with quadruple evaluation, and its repeat accuracy is +/- one increment with a measuring speed up to 82 feet per second, depending on the resolution.

Kübler by TURCK encoders use non-contact technology and can survive environments with high vibration (30g/10-2,000 Hz) and shock (500 g’s/1ms). The products can also be used outdoors, due to an IP 67 protection rating, wide temperature range and the weatherproof die-cast housing. The metal housing also offers improved shielding against electromagnetic interference.

A built-in LED provides a warning signal or an index pulse, allowing for simple set-up and diagnostics. Connections are made via a high-grade shielded PUR cable that is also suitable for cable track installations.

TURCK
www.turck.us

Performance improvements include stroke lengths to 300 in. with the maximum non-linearity cut in half. This features ±50 µm for nominal strokes less than 500mm,  ±0.01% of full scale for 500 to 5500mm, and ±0.02% of full scale from 5501mm to 7600mm. Shock ratings are to 150g and vibration rating to 20g. EMC severity for static, RF, burst, and line noise is Level 3; for surge, Level 2 and magnetic field immunity to Level 4. Additionally, housing protection is to IP68 for pre-wired cables and IP67 for connector models.

Other improvements allow easier and more flexible configuration options during setup. Dual bi-color LEDs handle double duty for diagnostics and as a setup aid for pushbutton scaling of the position outputs. Communicating to a PC over standard USB, Micropulse Plus outputs can be scaled, inverted, and configured for single- or two-magnet position, velocity, or differential position between two magnets. Intuitive software features a simple-to-use graphical interface that allows drag-and-drop adjustment of the output characteristics. Configuration files can be saved for backup, replication, or for emailing to remote locations. Manual adjustment without a PC is also possible using the included pushbutton tool and simplified setup procedure that minimizes button-pushing complexity while maximizing operational flexibility.
For more information, visit:  http://www.balluff.com/btl7-z

www.balluff.com

The Micropulse ProCompact rod-style transducer incorporates field-proven, non-contact magnetostrictive technology into a welded, hermetically sealed stainless steel housing providing superior long-term reliability and service life compared to competing contact-based sensors such as linear or rotary potentiometers.

The ProCompact is ideal for the following types of applications: hydropower and other wet applications, railroad maintenance equipment, steel production, sawmill applications, or any other application involving high humidity, ambient temperature variations, and high-pressure wash down.

The Micropulse ProCompact linear position transducer comes in standard ¾-in.-16 UNF (optional M18 x 1.5) mounting threads, allowing the transducer to be installed into hydraulic or pneumatic cylinders. Right out of the box, the ProCompact is environmentally protected to IP68. For even more demanding applications, the threaded fitting on the ProCompact housing can accommodate a cable protection system, offering environmental protection up to IP69K.
For more information, visit www.balluff.com/procompact

BEI Industrial Encoders’ new linear cable transducer provides digital position and speed feedback information in a rugged, easy-to-install package. Model LT25 cable transducer utilizes a flexible measuring cable mounted to an internal spring-loaded spool and a quadrature encoder output to precisely measure linear motion applications. The sturdy cable is made of nylon coated stainless steel for ultimate strength and has a measurement range up to 125 inches.

Easy to install, simply connect the LT25 cable to your moving equipment and secure the base to a fixed object. Hard to reach areas or worries about shaft misalignment are now not a problem. The LT25 cable transducer allows for easy reorientation of the mounting bracket or encoder connector position, giving users added adaptability to their installation. With an IP66 rating, the LT25 is a perfect solution for a variety of industrial measurement challenges including wet, dirty, or outdoor environments or applications where your measuring range travels over a harsh environment.
For more information, visit www.beiied.com/cable-transducer

Southington, CT – For high resolution, high dynamic measurement of position, speed and velocity, Baumer has introduced the MHXX Series of hollow-shaft, large-bore, magnetic rotary encoders. These robust, non-contact encoders contain no bearings, so measurement is contact-free and components do not wear. The IP67 rated housing and fully encapsulated read head electronics allow long-term, reliable performance in high shock and vibration environments.

MHXX Series Magnetic Rotary Encoders operate efficiently in a wide range of temperatures, from -40 to 100ºC. All products in the line are compact, featuring very thin rotors and read heads that adapt easily to the axis of rotation. Specifically designed for use on shafts from 20 to 740 mm, the encoders are designed to allow large clearances between the rotor and the sensing head for easy mounting. The encoder’s disk may be mounted using set-crews, clamping rings, or clamping fixtures.

These IP67-rated encoders withstand vibration to 30g and shock to 300g. All encoders in the MHXX Series are available with incremental or sine-cosine outputs and certain models are also available with an additional absolute output track up to 17 bits. MH Series encoders offer large (+/- 3mm) permissible axial displacement and large (0.1 to 2.2mm) permissible air gap tolerance depending on size of bore.

MHXX Series Magnetic Rotary Encoders can be used on equipment and machinery used in motion control, textile production, wood/timber processing, packaging, machine tool, medical, electric motor and general industrial applications.

For more information contact Baumer at (800) 937-9336, or email at sales.us@baumergroup.com.

www.baumergroup.com/cameras

Florence, KY – BIW Pulsed-Inductive sensors from Balluff only look like traditional resistive linear potentiometers. However, unlike linear potentiometers, BIW sensors use patented, non-contact technology to provide continuous, absolute, analog position feedback. Because there is no mechanical contact, wear is not an issue. BIW sensors are available at a price level equal to or lower than many linear potentiometers.

Like resistive linear potentiometers, BIW Pulsed-Inductive sensors are available with analog voltage outputs (-10 to +10V or 0 to +10V). But unlike linear potentiometers, these innovative linear position sensors are available with analog current outputs (0 to 20 mA or 4-20 mA) as well, without the need for external signal conditioning. This is important because analog current signals offer much better electrical noise immunity and allow for longer cable runs compared to analog voltage signals.

Balluff BIW Pulsed-Inductive linear position sensors are designed to be form-factor replacements for traditional resistive linear potentiometers, right down to the familiar sliding plunger. It also means BIW sensors are a perfect fit for linear feedback applications such as those found on plastic injection molding machinery, packaging machinery, hydraulic motion bases, and woodworking machinery. BIW sensors are also an ideal solution when low-cost, continuous position feedback is required on hydraulic or pneumatic cylinders.

For further information, visit: www.balluff.com/biw

Recent
advancements in field programmable gate array technology enable digital
servo amplifiers like the Danaher Motion S200 family to achieve current
loop bandwidths of 3 to 5 KHz.

Typical advancements include replacing hydraulic and pneumatic actuation with step or motor driven actuators, changing step motors to servo, or replacing brush servomotors with brushless servos. The change from a step control to a servo control is typically less stringent than a move from a hydraulic or mechanical system to servo control. Electrical expertise for step motors and step drives is often available within a company. But in-house experts may not be available for hydraulic and pneumatic controls. With training and experience though, altering technology does not have to be daunting.

This
single acting, uni-directional hydraulic cylinder system is simple,
consisting of eight parts. For bi-directional operation, a more complex
and costly system would be needed.

Decrease variance to increase repeatability
Assume for a moment that you need to flow a liquid, semi-liquid or molten material at a specific rate. Should the material viscosity change between batches, achieving consistency with a hydraulic or pneumatic ram could be challenging. One remedy is to connect a PLC to a force cell to control the force in an on-and-off format. This is often referred to as Bang-Bang control and works great with the thermostat in a house, but is not really intended for the control of precision mechanics.

You may supplement this type of control with an exotic fuzzy logic scheme to round out the instantaneous changes, but this is not much more than “chattering” an input or valve to obtain a reduced rate of change. A servo actuator can replace an air cylinder and control both force and speed with the aid of a servo amplifier and without any special or exotic components. The position, velocity and current of a motor are constantly controlled to the specific tuning parameters required for the application.

Know your requirements
A detailed understanding of the application’s motion requirements is imperative. This understanding includes the mechanics, electronics, software, and dynamics (kinematics). Should your system require a point-to-point move for the pick-and-place of an electrical component, it may not be necessary to reduce following error to the minimum. Such misapplication may result in more effort in the control system, which can cause other issues such as resonance or heat buildup in the unit under control. In the case of a contouring or printing application, such an error is a direct measure of the output quality and must be considered.

Simulations and breadboards can increase your understanding of an application’s requirements. Accurate simulations reduce the number of false starts and re-designs, both of which waste capital and tax the creativity of the group.

This
simple electric actuator system ensures consistent bi-directional
operation. OEM machine builders obtain a low cost, easy to install,
high-performing device. End-users receive better control over critical
machine operations, with excellent accuracy and zero maintenance over
the life of the machine.

A number of good simulation tools exist that can help significantly reduce design time. Physical systems can aid the simulation process but they can take a significant amount of time, space and experimentation. A physical breadboard is also subject to materials delays, internal staffing issues and capital expenditure limits. This is not to suggest that a breadboard should necessarily be avoided, as it can serve as the basis for determining whether a system is worthy of investment beyond the brainstorming stage without too much difficulty.

Use of simulation tools, such as VisSim from Visual Solutions or Motioneering and Model Q modeling software, let you vary the design to determine its viability and usability. Approximate force, torque, accelerations and frequencies can be analyzed prior to investing in material.

What not to overlook
When an upgrade is required due to obsolescence, there are some often over-looked performance issues that can make or break the project.

A brush-style moving coil rotary motor, for instance, may have longevity and power handling shortcomings, but its replacement can be wrought with obstacles too. It is not unheard of for applications to require velocity loop bandwidths in excess of three or four times the capability of standard digital servo amplifiers. Replacing one of these brush-style motors in a high performance application can still be done successfully.

Recent advancements in field programmable gate array technology allow digital servo amplifiers to achieve current loop bandwidths of 3 to 5 KHz. This high bandwidth enables a 1 KHz velocity loop or greater. The capabilities of such a system coupled with the right motors can achieve and even exceed that of earlier systems, while offering the wear and power handling advantages of brushless technology.

For example, in an electronic assembly machine at Universal Instruments, a component placement head needed to operate faster. This placement head is on the Radial Lead Inserter. The previous method of control was pneumatic, which limited the machine’s capabilities for several reasons including, but not limited to: environmental factors, compression time variances, valve actuation variation, and exhaust limitations.

To compensate for these variances, the old system used deceleration hydraulic shock absorbers, proportional cushioned air cylinders, intensifiers, and special exhaust reclassifying mufflers to remove atomized oil that could not be exhausted to the air.

In
this stamping press application the old method used a conventional
servomotor and gearbox coupled to the feed roll with a belt. The
Cartridge DDR™ mounts directly on the feed roll and eliminates the
gearbox, belts, pulleys, and mounting structure to hold it all
together. It was installed in less than 10 minutes. Accuracy went from
0.002 in. with the geared servo to 0.0005 in..

Changing to a servo system was not without challenge, but the use of a Danaher Motion special R-series motor met the application requirements without the need for shock absorbers, special valves, or other pneumatic parts. Since this machine was part of a sequence of operations, the consistency of move time and acceleration allowed other functions to initiate earlier, increasing the cycle rate as well. Life tests revealed other improvements. The lack of shock decreased the wear on some components, significantly increasing machine reliability and uptime. Set-up times for the

machine build were reduced. When evaluated in combination, the brushless motor and amplifier were more cost effective than the previous scheme.

This system was first modeled in VisSim which reduced the evaluation time. Prior to the simulation, no motor appeared to fit the application due to envelope constraints and performance needs. Using the model with a custom motor and standard amplifier, the application was deemed worthy of continuation. The result is the patented Radial Lead 8XT from Universal Instruments.

Danaher Motion
www.danahermotion.com

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