reverse engineering
giving the user tremendous freedom in measuring fea- tures best suited to tactile measurement. For example, API Services’ parent company in Rockville, MD, Auto- mated Precision Inc., makes a wireless hand-held probe called the vProbe that interfaces with their Omnitrac2 la- ser trackers. The volumetric accuracy of the Omnitrac2 system is ±0.0016" (40 µm) within a 5-m scanning range, while the probe can deliver 3D point accuracy as low as ±0.002" (55 µm).
Strand explained that, “The tracker shoots the laser to the embedded prism on the probe. There are no attached, articulating pieces. In order to orient itself in space, the probe has sensors that reference a gravity frame mea- sured by the tracker. The prism in the hand-held unit can we swiveled so that you can probe an area that might be hidden from your line of sight as long as the tracker can still see the embedded prism.”
Quick Work in the Real World
Kersen also said that with the possible exception of jobs on top of an airplane, a portable arm-based sys- tem can handle most of the scans required in field work.
“We just had a rush job for Southwest Airlines. What the industry refers to as ‘airplane on the ground,’ meaning the plane is grounded until the problem is fixed. A bird had hit the wing. They called at three o’clock. We had engineers on the scene at five. By then the airline had removed the sheetmetal covering the wing so they could get to the strut and cut out the damaged part. Our en- gineer rolled up to the wing with a portable CMM laser scanner, mounted on an extendable tripod. He scanned the area and created a model of what’s called the ‘bath- tub,’ an insert that would provide the required strength in the damaged section of the wing. We converted that to an STL file and then an Inventor file by eleven that night. The airline then cut a new part and had the plane flying the next day.”
The Corpus Christi Army Depot (CCAD) credits its NVi- sion arm-based laser scanner with cutting the time it takes them to reverse-engineer helicopter components from two weeks to two hours. That should make the taxpayer happy, because CCAD is the largest facility in the world provid- ing overhaul, repair, modification, recapitalization, retrofit, testing and modernization of engines and components for rotary wing aircraft. They’re keeping 30–40 year-old heli- copters in service, many of which were designed without CAD and lack even blueprint documentation. Like the system NVision used at Southwest Airline,
CCAD’s laser is easily moved by hand, but mounted on an articulating arm that enhances the accuracy. Vernon Hull, machine shop supervisor said it, “
...moves about the ob- ject, freeing the user to capture data rapidly and with a high degree of resolution.” Whereas it took days to tediously collect tens of thousands of points to define complex sur- faces with their CMM, the NVision scanner “collects mil- lions of points on the aircraft in only 30 minutes...We can now capture thousands of points every second, making it possible to more accurately define the part surface in a matter of hours. The net result is that we can get aircraft back into service faster.”
To CAD or not to CAD These case studies are a good example of both the speed with which a laser scanner can get you the 3D model you need, but also the necessity of having the right
Ï View of the damaged wing section on a grounded Southwest plane that had hit a bird.
LF22
AdvancedManufacturing.org
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 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116
