New NonContact LaserBased Gauge for Measuring Length and

New Non-Contact, Laser-Based Gauge for Measuring Length and Speed of Gypsum Board Stuart Manser Beta Laser. Mike

Non-Contact Laser Gauge Introduction n Technology of a Non-Contact Length and Speed gauge Describe how it works Two applications examples: n n Cut Length Cutter Control

Non-Contact Laser Gauge Traditional Length & Speed Measurements n n n Accomplished by using a roller that contacts the material being measured The material turns the roller as the material moves An encoder or tachometer is attached to the roller n Generates pulses as the wheel or roller rotates n Relies on friction between the material and roller

Non-Contact Laser Gauge Disadvantages Tachometers/Encoders n Error caused by slippage n n Recalibration n Dependent on friction Wheel pressure Product surface Diameter change because of wear Diameter change because of build-up Maintenance n Bearings and other mechanical parts wear out

Non-Contact Laser Gauge Laser. Speed History n n n Laser. Speed technology was developed in 1984 Aluminum/Steel Mills Small integrated gauge developed in 2001 n n Compact Lower Cost Easy to Install High Accuracy – 0. 05%

Non-Contact Laser Gauge System Concept FPGA- Signal processing PCB Laser diode assembly with temperature control Proprietary beams steering optics and receiving optics Measuring region

Non-Contact Laser Gauge Non-Contact Gauge Technology

Non-Contact Laser Gauge Non-Contact Gauge Technology Two laser beams cross at an angle 2 K K bisects the two laser beams Constructive and Destructive Interference cause a Fringe Pattern The Fringe Pattern consists of light (constructive) and dark (destructive) stripes

Non-Contact Laser Gauge Fringe Pattern Expanded § Constructive Interference occurs when two laser beams are in phase and add together to equal the original laser density - light stripe § Destructive Interference occurs when two laser beams are out of phase and the two laser beams cancel each other out - dark stripe

Non-Contact Laser Gauge Fringe Pattern Generation n Fringe Pattern looks like an elongated football Measuring region (Depth of Field) is where the fringe pattern exist Project this fringe pattern on the surface of the product to be measured

Non-Contact Laser Gauge Laser Doppler Velocimetry (LDV) Theory Fringe direction

Non-Contact Laser Gauge No Calibration Required n Wave length constant n n n Laser diode based system Laser diode is temperature controlled Crossing angle n of the laser is fixed and is created optically No moving parts in optics package Crossing angle is permanently fixed Fringe Spacing ‘d’ is fixed and cannot change

Non-Contact Laser Gauge No Calibration Required n Frequency measurement uses an all Digital Signal Processor n n n Autocorrelation algorithm High measurement rate High measurement accuracy High measurement repeatability Signal processor is all digital and has no drift or measurement error

Non-Contact Laser Gauge No Calibration Required n n Length is achieved by numerically integrating the speed Permanently calibrated with very high accuracy

Non-Contact Laser Gauge Non-Contact Gauge Block Diagram Dual-Beam Laser Interferometer Diode Laser Acusto-Optical Modulator Optical Beam Splitter Photo -Detector Product Received Light Receiving Lens (15 mm) Measurement Region Fringe Direction

Non-Contact Laser Gauge Cut-to-Length Application n n Gypsum board manufacturer Plant produces 4 x 12 ft (120 x 366 cm) boards Needed more accurate method for measuring length of wallboards after cut Used mechanical wheel encoders to perform cut-to-length measurements

Non-Contact Laser Gauge Problem n Contact method caused boards to crumble and stick to encoder n n Clean-up, repair, and calibration of encoders Discrete boards difficult to measure n n Changes diameter of roll wheel Damage to product 3 - to 4 -inch (7. 6 to 10. 2 cm) gaps between boards Inaccurate length measurements n 2% error

Non-Contact Laser Gauge Scrap Cost Calculation n n 260 production days per year 22 hours of production a day Line rate of 550 ft/min (152 m/min) Cost per unit length to manufacture material is $. 20* Current encoder accuracy is 2. 0% Total scrap per year: $736, 276 *Cost of material for example purposes only.

Non-Contact Laser Gauge Solution n n Installed non-contact laser gauge after the cutting system Controls cut-to-length accuracy and product quality n n 12” standoff distance Perpendicular to board n n Measures discrete product length 0. 05% accuracy No damage to product Dramatically decreases product scrap and material reprocessing Significant production savings Low cost of ownership

Non-Contact Laser Gauge Cutter Control Application n n Gypsum board manufacturer Needed to: n n n Accurately measure product length during production Perform precise cut lengths Optimize product quality

Non-Contact Laser Gauge Problem n n n Used mechanical contact encoders to measure product length during board cutting Signals sent from encoder via PLC to cutting system Mechanical encoder 2% inaccurate: n Wet, debris-laden boards caused slippage n Vibration caused encoder wheels to bounce n Damage to product surface and encoder Inaccurate length caused synchronization issues with cutter Frequent downtime to clean, recalibrate, or service encoder; reset cutting system Resulted in material loss and product quality issues

Non-Contact Laser Gauge Scrap Cost Calculation Scrap = amount of material produced/year x material cost/unit of measure x contact encoder accuracy (2%) Significant product loss and downtime costs to manufacturer

Non-Contact Laser Gauge Solution n - Installed upstream from cutting system - 12” standoff distance - Perpendicular to board n n Replaced mechanical contact encoders with non-contact laser gauge Accurate length measurements (0. 05%) Precise synchronization with cutting system Reduced a significant amount of scrap Minimized maintenance, decreased downtime

Non-Contact Laser Gauge Summary Non-Contact Laser Gauge Advantages n n n No slippage error or debris accumulation optical system and does not contact the product Direct measurement of product Permanently calibrated – Laser Interferometer Optical system No moving parts to wear out Accuracy: +/-0. 05% Repeatability: +/-0. 02%

Non-Contact Laser Gauge Summary Continued n Complete System in one small rugged package n n n 26. 25 X 20. 67 X 10. 5 cm 2. 54 Kilograms n Sensor Processor I/O Power Supply 24 VDC operation IP 67 protection Built-in water cooling ports

Non-Contact Laser Gauge New Non-Contact, Laser-Based Gauge for Measuring Length and Speed of Gypsum Board Stuart Manser Beta Laser. Mike