3D Measurements in confined spaces. API White Paper. 3D Measurements in confined spaces. Krones AG

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1 Krones AG It is a paradox of manufacturing that objects requiring the most complex and precise three-dimensional measurements often offer the least freedom of movement, making it difficult to obtain such readings. Cockpit equipment, filling systems, aircraft parts and railroad cars are all such examples of objects that require very precise measurements in their construction but also have large dimensions, hidden angles and tight spaces that complicate the process. This article describes how laser trackers, used as portable 3D measurement systems, can measure these large structures in space-restricted environments. The demands on 3D measurement systems are most apparent when they are used to measure large and precisely manufactured components that need to be built to exact tolerance specifications. A traditional 3D-CMM measuring machine capable of measuring a piece at least 10 meters long can cost several hundred thousand dollars. They are even more expensive if they are needed to measure longer pieces, which is the trend in many of these industries, most notably in aerospace. Meanwhile, these parts are built using fewer and fewer components, with the ones remaining getting larger, which helps them become lighter and stronger. One major drawback of these expensive measuring machines is that they are stationary, requiring the piece being measured be transported to it. This leads to high transportation costs and is sometimes impossible. A measuring machine alternative: the laser tracker Mobile measurement systems, such as laser trackers, can be taken directly to the manufacturing site and carry out measurements directly on the spot. Unlike stationary measuring machines, la-

2 the operation, remotely control the tracker. The most advanced laser trackers, such as API s Radian, also have an integrated camera that is able to detect targets called spherically mounted reflectors or SMRs that are located within the measuring field. Through this process, automated measurements can be taken with several targets at the same time, resulting in a considerable time savings. The camera can also be used to document the measurement process in video or still images. The size of a device is often not the only challenge for measuring it. Often, these pieces have an intricate layout that is just as difficult to measure, as shown here in the example of a device for the cockpit assembly. Only through a large number of measurement points on the device can it be ensured that the cockpit will correspond exactly to the specifications of the construction plans. Simplification of the manufacturing processes Bild: Pilatus Aircraft cockpit measurement. Open spaces in the cockpit assembly are measured using a spherical mounted reflector (SMR). ser trackers can measure parts before they are even cut out or molded in production. This ensures the integrity not only of the part, but of the entire manufacturing process and enables engineers to quickly make corrections or calibrations. Laser trackers have proven to be welcome alternatives to stationary measuring machines. Depending on their design and the model, many trackers can measure three-dimensional structures up to 80 meters long. Their mobility allows for a measurement range that is limited only by their ability to recapture a laser beam reflected from a target. Tracker operators inspect the structure of the component to be measured with the target and, to simplify The complexity of large machinery pieces can be staggering. More than 1 million holes are drilled in the construction of an aircraft. And they all must align perfectly. In the past, these holes would only be drilled after the shell of the aircraft had been laid onto the skeleton only then could the exact position of the holes be known. This manufacturing process is extremely time-consuming and complicated. It also has to be carried out from the inside. But by using a laser tracker, every coordinate can be transferred from the CAD system to the device. This means that all the holes can be drilled in exactly the right position during the manufacture of the outer shell. With measurement distances of up to 80 meters, the API laser tracker is also capable of covering the complicated fuselage and wing assembly of large aircraft. API s tracker has a revolutionary design that allows it to cover such a wide range despite its small size. In this device, the laser Radian: API s newest laser tracker The Radian is the latest generation laser tracker from API. Its built-in video camera allows users to document the measurement process in video or still images. Its wide-angle tracking and ability to pick up multiple targets makes it the most versatile measuring system available. Radian Laser Tracker

3 beam does not have to be diverted by a mirror a single time before leaving the tracker head. The flexible installation and set-up capabilities in the system, which is only around half the size and half the weight of its competitors, allows for easy measurement of points that are difficult to access. Measurements inside systems When measuring large components, it is often essential to install the laser tracker inside the system itself, as some of the measurement points cannot be reached from the outside. It makes a weighty difference whether a laser tracker weighs more than 30 kg or is lighter than 12 kg, as is the API s Radian. Another critical difference between the Radian and other trackers is the Radian s ability to measure very steep angles from above or below. Often, there is not enough room to set up the 3D measurement system at a point far enough from the object to pick up these measurement angles. This is common in vacuum chambers, where a conventional tracker would have to be rearranged up to 10 times. With a vertical opening angle of 137 ( ) degrees, API laser trackers have the largest measuring angle of their class. This is an important benefit when measuring self-contained systems, such as aseptic fillers in a bottling plant, where a need to keep the machinery area sterile leaves no place for a tracker to be installed. In that case, the tracker carries out the measurements the machine room through opened doors or windows. Many manufacturers already consider how to integrate laser trackers into their measurement process, often beginning as early as when they are designing their devices. For example, designers at Airbus were able to determine how much a component should weigh by creating a special opening within the support construction. The measurements taken allowed Airbus to simulate the weight of the fuselage and made it possible to measure the lightweight component s support under realistic production conditions. Additionally, the laser measurements were able to help Airbus designers reference where high-precision measurement adapters made from nickel silver that are used in production to hold the mounting pins for the fuselage are produced with a longitudinal accuracy of 1/100 mm. The measurement adapters make it possible to reference these in the aircraft coordinate system. Precision is also required in the construction of compressors. A high point density is required in many cases when measuring geometries, which in turn are not scanned for reasons of accuracy, but are always processed with single-point measurements. For example, the measurement of a bearing hole with a diameter of 1.3 Pilatus Wing assembly. These are among the largest components in the aircraft construction. Krones AG Measurements on an aseptic filler. The measurement system is set up outside the machine room for sanitary reasons.

4 meters requires up to 160 individually measured points. This is accomplished much more easily when one person can take the measurements with a laser tracker. Carried out in this way, the comprehensive measurement of a complete engine s shape and position will only take about two or three days. And for particularly large engines, the tracker can be set up inside the unit itself. The low installation height of the API tracker head (36 cm) is an advantage here. Choosing the installation site Deciding where to place the tracker is an important consideration. It is sometimes necessary to mount the tracker at a higher level in MCE Measurement of an airplane component. Openings in the support structure allow the laser beam to catch its taret. MCE Component measurements at Airbus. This laser tracker is measuring the simulation weight to determine how sturdy the aircraft fuselage must be. order to ensure an unobstructed view of the area to be measured or to be able to measure inside the object. Many bottling plants, for instance, install laser trackers near the ceiling. Manufacturers of turbine inlet housings often mount the measurement on the housing itself in order to be able to measure the interior. In other cases, such as compressors set up in the open air, the use of maintenance platforms with a height of up to 6 meters is also required, depending on the size of the machines. Temperature sensors and a weather station integrated into the laser measurement system prevent environmental effects from skewing the results of NEAC Measuring from inside the part. Stationary measurement systems are often unable to get an accurate readings with a few hundredths of a millimeter, which is often necessary on compressors and other devices. A portable tracker makes taking measurements easy and a single beam can get accurate readings for objects up to 15 meters in length.

5 Summary This paper has discussed how the laser tracker offers its fullest advantages where complex components and systems have to be measured with high precision in confined spaces. As a step in the production process, 3D measurements can be carried out reliably and with significant time and cost advantages. This faster, more cost-effective approach replaces the tedious, manual measurements that would require people to crawl and stretch around the component. In some cases, laser-based 3D measurements have led to the development of entirely new production processes, including in aircraft production and even roller coaster construction. Today, laser trackers have become an indispensable part of modern 3D measurement technology. PWT Measurements with a laser tracker. The tracker is mounted at the top right edge of the inlet housing. the measurement. The measurement system is also completely encapsulated and does not require any active temperature compensation, such as controlled fans or ventilators, which are needed in conventional systems in order to keep the thermal expansion under control. Saving space: the tracker used for service work Fastening Systems for Confined Environments Right: Magenetic Mount- The API laser tracker in a headfirst position, fitted with a magnetic foot. This is useful for the attachment of laset trackers to magnetic surfaces, such as tool machines or machine beds. As useful as a portable laser tracker can be in measuring components during their construction, the versatility of a portable Bild: MCE tracker becomes all the more important when it is being used to measure fully built and operational objects on-site for maintenance or calibration. Not only will the a portable tracker be able to navigate the layout of a modern factory floor, it is also easy to transport fitting right in the trunk of a sedan. Compared to disassembly and shipping, this approach offers substantial savings. At one time, two weeks was required for alignment work on the foundation using levelling units, yardsticks and fine spirit levels. Now, these tasks can now be completed in half a day using a portable, laser-based 3D measurement system. API Bild: PWT Top Left: Mounting System Leveling Base - A base plate is used to install a tracker with a flat mount. The mount is afixxed by adjusint three screws.

6 IFM Laser Achse ADM Laser Bilder: API The Radian Right: The Radian design consists of just three main parts, which is fewer than other trackers. With just three parts, the Radian offers superior thermal controls, a better structural integrity, a lighter weight, and much improved accuracy. Left: the laser beams out from the Radian tracker without being deflected by a mirror. Krones AG Bild: API The API laser tracker (mounted on the pole in the upper half of the picture) is positioned to get an unobstructed view of the manufacturing process for a filling machine assembly line. About Automated Precision Inc. (API) Founded in 1987, Automated Precision Inc. Designs and builds some of the most advanced measurement and sensor systems, such as laser trackers, 2D and 3D systems and steering switches for coordinate measurement machines. API pioneered the laser tracker field with the invention of the self-tracking laser interferometer, which is the foundation of laser tracker technology. API products are used by the world s largest companies, especially in the automotive, aviation and aerospace industries. API is headquartered in Rockville, Maryland. Its European headquarter are in Heidelberg, Germany. It also has offices in India and Brazil. Contact: Rainer Lott Automated Precision Europe GmbH rainer.lott@apisensor.com Telefon: 06221/