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Original article date: May 2001
If you can save your work when all about you
Are losing theirs and blaming it on Bill
If you can trust your scripts when others doubt you
And keep well hid your list of those to kill
If you can wait and not salute (three fingered)
Just ‘cos the hour glass goes on too long
Or being “blue screened” not give way to hating
Though many times the urge is oh so strong
If you can dream of programs that are faultless
Yet rise each day to play the usual game
If you can meet with Smartsuite and with Office
And treat those two imposters just the same
If you can watch the programs you have crafted
Abused by users till they creak and fall.
Or watch the project you have worked for, shafted
Because the poxy budget was too small
If you can make one heap of all your hard disk
And risk it all without a backup done
And lose, yet start again with Windoze boot disks
And never breathe a word when you get home
If you can force your PKZIP and DRIVESPACE
To get you through long after disks are full
And so work on when there is not a byte free
except a net-based drive somewhere in Hull
If you can meet accountants yet stay human
Or meet the boss, nor lose the techie touch
If office politics can never hurt you
And users count on you but not too much
If you can keep the unforgiving system
To 40 hours a week of uptime run
You are the guru, one in fifty million
And what is more, you’re in demand, my son.
Original article date: February 1999
Built to a modular concept Mayr Transmissions’ Smartflex coupling is optimised for the requirements of servo drive lines and offers the machine designer the optimum flexibility with minimum stockholding.
Servo applications for direct drive lines are very common today. The vast increase in quantity has made the drive lines more and more economic. This has called out for a more economic but still high quality servo coupling.
The Smartflex coupling consists of a steel bellows clamped on shaft bushings by clamp collars. For installation the parts are put together and frictionally locked by clamping just one bolt each side. Hence blind assembly is possible. The clamping ring hubs are locked to the shaft frictionally by tightening the clamping bolt. This assures a backlash-free torque transmission between input and output shaft.
The modular concept allows a number of different components to be stocked without needing to stock a variety of complete couplings with different hub bores. Different shaft diameters are accommodated by a range of hub bushings of different bore.
The multiple layers of the steel bellows of the Smartflex provide extremely high torsional stiffness yet still compensate for larger shaft displacements with low restoring forces. This ensures true positioning of the drive and protects the shaft bearings from premature failure due to excessive radial loads.
Made from aluminium the hubs together with the light metal bellows provide an extremely low moment of inertia making the couplings suitable for highly dynamic fast reversing drives.
- Mayr Transmissions
- 01535 663900
Original article date: June 2000
A new multiaxis distributed controller has adopted the FireWire comms link, bringing faster data transfer rates that traditional buses
Motion controllers often have to operate in less than ideal industrial environments. The production or manufacturing floor can be tough on the controller, both physically and in terms of the demands on its systems.
National Instruments reckons it has addressed both of these issues with the FW7344 multiaxis distributed controller. For one, it’s a sturdy, self contained device more than able to cope with the physical rigours. And importantly, it is the first product of its type to adopt FireWire as a communications bus.
With FireWire, the host PC monitors motion at a much faster rate than is possible with other serial buses. Once programmed, the controller monitors motion independently from its host PC. And because of this independence, and the use of FireWire, it performs exceptionally well at high speeds.
“Fast communication is especially important when your motion is tightly coupled to other processes on your PC,” says Mike Darden, motion control product manager at National Instruments. “The FireWire interface on the FW-7344 has the speed to integrate the controller into a high performance computer-based data acquisition or industrial automation system.
The FireWire bus transfers data and 400Mbps, which is markedly faster than the current Universal Serial Bus, which transfers data at 12Mbps, or RS485 which bottoms out at just 10Mbps. With the Firewire interface, you can daisy chain as many as 32 FW-7344 controllers together. PCs lacking FireWire ports can be easily equipped via conversion boards.
- National Instruments
Original article date: May 1999
Introduced recently to a UK audience at the MTEC (Measuring Technology) Conference and Exhibition Shape Tape is set to change the way shapes and surfaces are measured. Alan Quinn reports
Imagine an array of fibre optic sensors embedded along a flexible ribbon of tape? The result of innovative research from the Canadian Space Agency from which it is produced under licence the remarkable Shape Tape sensor has knowledge of its position in three-dimensional space. As a result it can be used for demanding measuring tasks replacing the need for a plethora of sensors and transducers.
Output signals from the tape array are used to construct a three-dimensional real-time model of the shape on a monitor for instant observation and analysis. The tape design allows six degrees of freedom measurement at any point along the ribbon which can be a metre or more in length. The sensor array knows its position relative to a fixed origin point on the tape and can measure static or dynamic shapes including curves and twists.
Developed by Measurand Inc and marketed in Europe by RDP Electronics the simple rugged yet innovative construction means that one tape can replace large numbers of discrete sensors such as load cells accelerometers pressure and displacement transducers. Experiments can be set up more quickly and a test structure can be changed in minutes.
Shape Tape is suitable for tasks in biomechanics image capture film animation 3 CAD transport crash testing virtual reality and marine design for example.
The standard bandwidth is 1.6kHz but systems up to 10kHz have been developed. Resolution of conversion is 0.01% of range limited by the A-D conversion process.
- RDP Electronics
- Tel: 01902 457512
- Fred Thorneycroft
Original article date: April 2000
An encoder with millions of variants from a single disc is on offer from Stegmann. Alan Quinn considers the implications for encoder users
Perhaps the greatest problem with the development of encoders has been that all manufacturers have needed a large number of etched discs – one for each number of incremental lines – to accommodate the resolution requirements of all of their users.
In conventional designs, the etched discs have to be cemented to the shaft, which means that the shaft type and its profile have to be determined before the product can be made. The natural result of this, along with fact that an enormously wide and varied range of components have to be connected around the shaft/disc assembly, is that an extremely large number of different mechanical procedures are required.
This has resulted in obvious difficulties, both for the manufacturer and the end user. Only order-specific production is possible, with the inevitable consequences on delivery lead times.
Now, with an encoder system called Coretech, Stegmann claims to have changed all this. Coretech uses a disc with an electronically applied line pattern which is imposed as part of the manufacturing process itself. This means that only one type of disc needs to be held in stock and – it sounds silly to say it – any one of 10 million possible versions can be generated, with only 100 individual components.
Stegmann isn’t saying too much about the actual production process itself but, in particular, the discs can be despatched within 48 hours, way in advance of the current industry benchmark. The user can choose from a very wide range with much improved quality and reliability. And there is no price premium, whether the customer requires a solid or hollow shaft, servo or face mount, absolute or incremental.
Original article date: November 1999
Alan Quinn reports on a compression spring gauging system which is now available off the shelf for the first time
Previously only available through Cadar’s bespoke gauging service, the company’s spring compression gauge is now available as a standard product for the first time. Although primarily designed to measure car suspension springs, the gauges can be used to measure a large range of compression springs.
Wherever possible, the approach is to measure components in the same manner as they are used in operation. The gauge has the ability to measure loads in seven axes at any point between free condition and bound state. it can also scragg (pre-stress) springs to loads of up to 25kN.
The spring compression gauge consists of a support frame, a vertically mounted electrically powered ram with an interchangeable spring locator for the major spring bore and a table with an interchangeable locator for the minor spring bore. The movement of the ram is monitored by a glass scale linear encoder and the loads are measured by a strain gauge, upon which the minor bore locator is mounted.
The spring compression gauge has been designed to be very strong and robust, thus allowing it to operate in a shop floor environment. Safety is a prime concern and it is for this reason that the operating area of the gauge is fully enclosed by three clear fixed panels and a sliding door. This door must be closed and for reasons of safety the gauge will not operate with the door open.
The gauge control software is configurable by the user to allow for custom details to be added. Three proprietary software packages are available for use with the gauge: Variables, Checkmate or the new QS-Pro package. Measurement details are displayed on the Cadar Checkstation industrial computer which is supplied as part of the kit.
Original article date: September 1997
The relative merits of 4-wire and 2-wire signal/power transmission configurations in industrial sensors are the subject of some debate among controls and plant maintenance engineers.
In the 4-wire scheme, a pair of twisted wires is dedicated to the precise transmission of a 4-20mA current signal linearly proportional to the variable being sensed, while two additional wires are reserved for supplying power to the sensor.
The 2-wire method, on the other hand, uses the same pair of wires for transmitting the output signal and powering the sensor’s circuits.
To minimise signal noise (maximisation of S/N ratio), which is especially important in applications below 760°C, Calex has designed 4-way circuits into its infra-red thermometers. The resulting unlimited powering current allows for extremely low-noise circuit design and component selection.
Powering, noise and installation trades-off are listed. Clearly, a 4-wire sensor is the best application for all applications where process control accuracy and stability are early considerations.
In areas where a 2-wire device is being replaced by a 4-wire one, installation of the power supply at the sensor location will eliminate the need to rewire through conduits with existing 2-wire lines, and those wires may be used for signal transmission.
Table 1 Power/Noise Considerations
|Power Supply||12VAC||16-40VDC (must be regulated)|
|Circuit Powering Current||Unlimited||3.5mA maximum|
|Processing Electronics||Very low noise||Fair|
|Temperature Signal Accuracy||Not affected by power supply fluctuations||Affected by power supply fluctuations|
Tel: 01525 853800
Fax: 01525 851319
Original article date: March 2000
A new design of web tension transducer can determine the true web force as well as the resultant angle
Available in ranges from 0-5,000lb to 0-20,000lb, the HTU web tension transducer from Nobel Systems utilises a two dimensional approach to web tension force measurement. The subject of a patent application, the technique allows both the true resultant web force and the resultant angle to be accurately determined.
The HTU transducer measures web tension forces applied across a roll, using integral horizontal and vertical axis sensors. Not only does the approach permit installation and measurement at any mounting angle or roll orientation, it also forms the basis of an expert diagnostics system that produces the highest level of web tension measurement confidence.
The HTU is machined from a high strength corrosion resistant stainless steel to yield a low profile single piece construction that incorporates tubular sensing sections at each end. Two full Wheatstone Bridges are mounted internally to each sensor and provide output signals in the X and Y planes that are externally, vectorially summed to determine the magnitude and direction of the resultant force. Each bridge is temperature compensated to 250degF, and dead weight calibrated to precision accuracy. The cylindrical sensing sections are sealed to meet IP67 requirements.
Environmental sealing ensures long term reliability in humid, wet or washdown locations.
Retrofit installations are simplified thanks to the low profile height of 36.8mm, resulting in a negligible change in the line profile. The HTU can be mounted directly to the framework with an optional pillow block adapter plate or it can accept top and bottom adapter plates.
HTU transducers are calibrated and certified with matched output signals to permit on-site pushbutton system calibration, providing minimum start-up time and maintenance-free operations.
Applications for the transducer include paper, plastics, roofing, metal strip forming and rubber forming machines. It will also offer benefits on mining conveyors.
- Nobel Systems
Original article date: September 1999
The testing and development is up and Renold’s remarkable strain gauge for drive chains is now looking to perform in anger. Alan Quinn explains what it’s all about.
An intelligent chain link capable of collecting load data and predicting chain life on actual applications has been jointly developed by Renold Chain and the University of Newcastle-upon-Tyne. Whilst correctional strain gauging techniques have been used for many years it has not previously been possible to capture the actual loads and calculate stress on real applications. Monitoring has only been possible in laboratory conditions where peak and shock loads unique to each individual machine cannot be measured.
Branded Renold Smartlink the new units may be fitted to various types of transmission or conveyor chain to record dynamic loadings for subsequent analysis on a PC. In critical applications Renold engineers believe that it could be possible to fit the Smartlink permanently and to use sophisticated computer links to allow engineers to receive vital chain performance data off-site. Areas expected to benefit most include the offshore and leisure industries heavy lifting applications and general conveying.
The data recorded by the Smartlink system enables engineers to identify precisely the location of both peak and shock loads measure stresses and calculate an optimum chain size for each application. The same methodology can also be used to determine the causes of premature chain failure with the obvious safety benefits and cost savings for end users.
The system consists of the Smartlink unit currently about the size of a small calculator and a hand-held remote controller with a transmitter and receiver. Depending on the data required the hand-held units are used simply to select the required programme and then transmit the instructions to Smartlink in a similar way to programming a video recorder. The collected data is then recovered by the hand-held units and stored on an easily removed chip that can be sent to Renold Chain for analysis or alternatively downloaded onto a PC and analysed on site.
- Renold Chain
- Yvonne Alexandser
- 0161 437 5221