AUTOMOTIVE DESIGNSECTION TITLE
EXPERTISE ENGINE
Terry Arden discusses custom non-contact engine volume gauging for Tier 2 and 3 component suppliers
F
or automotive component suppliers that need to verify high tolerances on medium-sized internal combustion engines (ICEs), an expert in the sector has designed a 3D non-contact inspection method to replace manual measurement approaches. Tis automated non-contact 3D solution, called Gocator Volume Checker, combines several technologies to achieve high-speed, accurate volume measurement of engine cylinder heads and piston bowls. Volume gauging is an important application in engine development. Each cylinder in an engine block has to be measured for correct combustion volume. Although CAD data can be used to determine nominal volume, compliance testing requires the acquisition of a large number of measurement points, their connection by line or curve approximation, and finally computation of volume displacement.
CONTACT-BASED METHODS Tactile coordinate measuring machines (CMMs) can accomplish volume gauging with a high degree of accuracy. However, this method can take more than two minutes per chamber, and all chambers need to be measured. As a result of the slow speed and high cost of CMMs, the vast majority of manufacturers use liquid to measure engine volume. Acoustics and
pressurised air are less commonly used contact-based methods. All three of these traditional methods are time-consuming because there is considerable set-up time involved, and only one cylinder can be measured at a time. Additional time is required for clean up after the measurement process is completed.
THE ADVANTAGE OF OPTICAL METHODS Optical methods based on structured light (fringe projection) offer a 3D scanning method that is non-contact and area based. 3D scanning with this method is significantly faster (seconds, not minutes) and produces much higher density 3D data, representing a more accurate shape of the part. Snapshot sensors are common devices that deliver this type of 3D scanning technology. A structured light 3D snapshot sensor projects a line pattern onto the cylinder head of an engine block. Te line pattern is recorded by a camera from an optimal angle, yielding information on the cylinder’s surface topology calculated from the deformation of the projected lines.
Multiple GoMax accelerators can be
used to speed up engine cylinder and piston bowl volume gauging cycle times
Tere is a clear advantage to using
structured light for quality inspection. Namely, when blue-LED stripes with smooth value gradients are projected and moved across the engine block in close steps, the analysis of these values allows for a magnitude better position resolution than the single point measurement typical of CMM probing methods. Stripe pattern projection provides
Volume Checker components
coordinate resolution down to 1/50 of the projected stripe width. Tis means the cylinder head can be fully inspected with the acquisition of just a few dozen images with slightly shifted stripe positions (i.e. phases), which can be accomplished in just a few seconds.
www.engineerlive.com 11
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76
