EVOLUTION OF THE SPECIES: InteliSENS SLmini. Author and copyright: Danny Buelens.

Transcription

1 INTRODUCING intelisens Non-Contact Laser Doppler Speed and Length Measuring Technology for Converting, Woven and non-woven, Paper, Film, Foil and Process Industries Author and copyright: Danny Buelens In all these industries, price pressure, and fierce global competition instigates manufacturers to reduce cost and waste, and manage delivery lengths better and more accurate. In the converting, woven, non-woven, paper, film, foil as well as many process industries, speed and length of product is measured by contact encoders. In most cases the product is contacted by a wheel and the wheel rotation is translated into encoder pulses, these pulses are counted by an electronic counter or by a PLC counter. Depending on the circumference of the wheel and the number of pulses generated for each rotation of the wheel/encoder, the applied calibration factor, etc the length or speed is measured. In all industries this method of length or speed measuring is used since over 100 years More and more, in the EU, as per EU Directive 2004/22/EG, the European Measuring Instrument Directive, MID Group 9 Material Measures of Length, there is a requirement for using MID Certified Systems, for the final measure of shipping lengths. MID Certified Systems are Metrological systems, with EU wide Authorisation, and bearing the CE-M Label (Legal CE Metrology). Mechanical Measurement = Reduced Accuracy All contact methods of measuring Speed or Length, are associated with problems, such as: - reduced accuracy - problems associated with slippage - material stretch inducing large errors - wear of the measuring wheel - contamination of the measuring wheel - frequent need for calibration - encoders wearing out - Not possible to communicate with the sensor by modern communication interfaces. As far as managing product length, the manufacturer is faced with problems such as: - Shipping excess material due to slippage - Measuring errors due to product characteristics such as stretch, surface irregularities, etc EVOLUTION OF THE SPECIES: InteliSENS SLmini In many process industries, and many applications, Certified Non-Contact Laser Doppler Systems can handle far higher speeds and/or accelerations then any mechanical system. MID Certified systems help the manufacturer to demonstrate compliance to the National and EU Inspectors of weights and Measures, and the manufacturer can demonstrate compliance to certified minimum accuracies towards his clients. Any manufacturer knows to what disputes on issues of non-compliance, with clients, of supplied length might lead to, and the resolutions on such complaints are often very expensive

2 APPROVED NON-CONTACT, SPEED AND LENGTH PROTON intelisens LASER DOPPLER TECHNOLOGY PRINCIPLE OF OPERATION Two laser beams are emitted from the gauge head. The measured product should be positioned at the point of convergence of the two laser beams. Proton Products InteliSENS SL and SLR Series of Non-Contact Laser Doppler Velocimetry (LDV) Speed and Length gauges measure products that are made in a continuous process, incl. paper, foil, plastic sheet, film, woven, non-woven, food, metal, and all other products. The gauge uses two laser beams to create a laser Doppler fringe on the product surface. Receiving optics collect the reflected Doppler signal which is then processed using advanced high-speed Digital Signal Processing to ensure the measurement data is accurate, reliable and repeatable. The gauge measures in the toughest production environments. The gauges are extremely easy to install, set up and integrate into an existing control system, or can be used as a stand-alone system. All outputs are integrated within the Sensor. Calibration is permanent! A Doppler light pattern is created on the product surface. Defects passing through this pattern generate a particular light frequency, which is detected by the gauge head. The intelisens SLmini or SLRmini gauge is typically used to measure the speed (and therefore length) of strips, foil, sheet, plastics, woven and non- woven, textiles, rubber, foodstuff, metal, web, etc Applications in process industries are countless.contact encoders result in low accuracy, over-length giveaways due to slippage or unwanted product marking, the intelisens SLmini or SLRmini provides the solution and quick Return on investment. The gauge emits two laser beams at a moving object and analyses the reflected light to obtain extremely accurate measurements. At the point where the laser beams cross, a pattern of light bars is projected onto the surface of the measured object. This pattern is not discernable to the human eye because it is so fine. The human eye sees just a red dot or red line. EVOLUTION OF THE SPECIES: InteliSENS SLRmini The gauge relies on defects passing through this Doppler bar pattern to generate a characteristic frequency proportionate with the speed. This frequency is detected by the Avalanche Diode inside the gauge head, and the Digital Signal Processor calculates the speed of the moving product.

3 UNI-DIRECTIONAL and BI-DIRECTIONAL Systems A Standard Laser Doppler Velocimeter (LDV) Gauge like the intelisens SLmini cannot measure down to ZERO SPEED and cannot differentiate in Direction of movement. Most processes however, cannot change in direction, hence the fact that the intelisens SLmini Standard Laser Doppler System cannot differentiate direction of movement is mostly not an issue at all. However intelisens SLmini has a minimum speed. The reason is that a Doppler signal is not available at stationary object. It requires a minimum speed to generate Doppler. The minimum speed of the Standard intelisens SLmini is nevertheless very low, typically 10 to 20 times lower as with a competing system, i.e. only 0.1/0.2 m/min. COMMON SPECIFICATIONS: intelisens SLmini AND SLRmini Accuracy Better than 0.05% Repeatability Better than 0.02% Acceleration >1000ms 2 Scanrate 200,000/s Update rate 0.02ms (20µs) Power 24 Vdc, 8 Watts Protection IP67 Temp. Range 5 C ~ 40 C The BI-DIRECTIONAL intelisens SLRmini SERIES of Proton Laser Doppler gauges can detect the direction of motion (and hence provide add and subtract capability in length count, and operate as from ZERO SPEED. The intelisens SLRmini SERIES have a unique accousto-optic modulator build-in (aka Bragg Cell) that modulates the laser at 40MHz. This is the Bragg Frequency. So at stationary object, the resulting Doppler matches exactly the Bragg Frequency and this is ZERO SPEED. As from the smallest speed of m/min the system can see a change in Bragg Frequency, Hence, it detects speed and displacement as from ZERO SPEED. Further, as there is a reference Doppler available as from Zero Speed, the direction of movement is automatically detected. Dimensions Weight digital inputs relay outputs Serial I/O CANbus Pulse outputs Optional comms L x W x H 140 x 105 x 50 mm 1 kg 2 x Fixed: Laser Enable and Shutter enable + 3 extra Programmable Shutter status + 2 extra programmable And Ethernet TCP/IP Connects to Proton Products range of SiDI-CDI Color display 2 x differential outputs or 1x quadrature output, Up to 1 MHz frequency Profibus or ProfiNET or Industrial Ethernet IP or DeviceNet The Smallest Laser Doppler Sensor in the world SPECIFIC SPECIFICATIONS intelisens SLmini and SLRmini Series: SLmini SLmini SLRmini SLRmini Typically 3 times smaller as alternative units, as big as the footprint of a mobile phone Min. speed in m/min Max. speed in m/min Stand-off in mm Depth of field in mm / /

4 A GENERAL MISCONCEPT: CALIBRATING A MECHANICAL WHEEL COUNTER HOW ACCURATE IS A WHEEL? Yes, indeed how accurate is a wheel? In general speed or length metering wheel have typically a circumference of 250, or 500mm. This means that every rotation of the wheel results in a displacement of either 250, or 500mm. In practice an encoder is used to count the wheel revolutions and to provide some basic resolution. Assume a wheel with 500mm circumference and an encoder with 500 pulses per revolution. Then the electronic pulse counter will attribute 2 x 500 pulses as 1000mm product displacement so with 1mm resolution, quite good. Is it really? Assume the wheel is not 500mm circumference but only 499mm, so every rotation of wheel, there is an error of 1mm, or 2mm every 1000mm. But during acceleration, deceleration and at speed, does the wheel moves at the product speed? You wish it would, but it does not, physics come in, the laws of inertia there will always be a magnitude of slippage, small or severe that is the question. How do you calibrate your mechanical wheel counter? Very well, but how do you calibrate for the elimination of slippage if you can you are in the wrong profession, you are eligible to re-write the laws of physics and become overnight billionaire. So forget to calibrate mechanical wheel counters, it is a pipe-dream. So how much is 1 meter under dynamic process conditions? But you do sale per meter? You are aware product slips through, un-counted? This slippage could be on the profit side of your balance sheet is your management aware of this? Calibrating mechanical wheel counters is a fairy tale. Engineers know that the product slippage element (the speed difference between object surface speed and contact wheel speed) cannot be eliminated; neither can be reliably compensated for. It is like speeding in traffic, police laser speedguns and radar units all over, the friendly police officer will give you a correction as they know that your car speed indicator lies a bit this in function of tire wear. How accurate is a wheel? APPLICATIONS: Proton installed near to intelisens Laser Doppler Non-Contact speed and Length Sensors worldwide in various Industries. Our clients are medium to large industrial companies. intelisens units were introduced where mechanical encoders were problematic, not accurate enough, or simply where a contact system cannot be used. In certain Industries contact with object is not even possible. As an example: Hot Metallurgical fields or Food Industry, etc Applications are hence too much to list, but hereby a limited summary: Coil, Spool or Reel length control in wire, cable, tube and hosing industries. Length control on intermediate production processes in the cable industry. Excess Fibre Length control in the Optical Fibre Industry Production of building materials: Bitumen Roof coverings, Plaster boards, extrusions and profiles for construction, etc Length and Speed control in the Metallurgical Industries and Hot Metal Industries. Hot and Cold Rolling applications in Steel, Aluminium and Metal Alloys Industries. Metal Profile and Metal Tube Manufacturing. Production of woven or non-woven materials. Webbing, Film, Membrane, Foil, etc Industries. Paper and Packaging Industries. Food Industries Precision timber industries Automotive Industries etc. With the intelisens SLmini and SLRmini Series, PROTON did not only introduce the smallest noncontact Speed and Length Sensor in the world, but also the fastest. With a speed update rate of 0.02 milli Seconds the system is 25 to 50 times faster as competing equipment. Speed does matter, as to measure length accurate the ability to measure any speed variation does matter, especially during accelerations and decelerations That this technology comes at an attractive price improves the R.O.I. even better.

5 IMPLEMENTING THE TECHNOLOGY Typical Applications in the process industries In all processes where cumbersome contact speed and/or length encoders are being used, the wheel and the encoder can be RED CROSSED. The wheel and encoder can be replaced by a intelisens SLmini or SLRmini non-contact Laser Doppler speed encoder. The cable that otherwise goes in the contact encoder can be plugged into the intelisens SLmini non-contact encoder. Your benefit: Accuracies better then 0.05%, typical within 0.02% No product slippage, no material give-aways No drift, No need for calibration A rich choice of communication interfaces for your process engineers Return of Investment within a few weeks. In a very wide range of process industries, such as in converting, web, foil, film, sheet, woven and nonwoven, paper, packaging materials, laminates, food, rubber, automotive, etc Industries, it is paramount that the length and speed measurement is performed with the highest confidence, so that the final shipping lengths are within consistent close tolerance. Moreover, many processes require precision balancing of speeds, speeds which cannot always be tracked precisely due to the physical properties of products, stretch induced by mechanical Sensors, etc. RETURN ON INVESTMENT The Return on Investment (ROI) is often only a few weeks or a few months. The Savings that can be obtained are multi-fold, by: Minimise Excess Shipping Length Avoid Shipping Shortages Avoid product waste Eliminate costly maintenance Eliminate frequent checks on calibration Minimise machine downtime.