- 注册时间
- 2009-12-25
- 最后登录
- 2021-7-10
- 在线时间
- 3302 小时
- 阅读权限
- 200
- 积分
- 10
- 帖子
- 13416
- 精华
- 1
- UID
- 2036
|
Aerospace Engineering October 2003 25 Tech focus Airbus chooses Makino equipment for A380 wing rib There’s a big change under way in how aircraft are assembled, a fact well understood by Airbus as it builds the A380 with help from Makino. “The trend to monolithic parts is increasing,” said Chris Harland, the A380 Wing Rib Project Manager at Airbus in the United Kingdom. “We must achieve economic run quantities of a single piece. It is now about process control due to high cost of individual pieces. Large batches and delays in inspection are a thing of the past due to the high potential cost of quality. It is no good to say, ‘we will inspect it later.’” To meet these stringent requirements for the A380, Airbus Filton UK has created an advanced wing ribmanufacturing cell utilizing the Makino MAG-Series equipment. The A380 wing rib manufacturing team set specific objectives when outlining the scope of work for the new cell: • Quality—low scrap rate, low concessions, high process capability, and inprocess verification. • Cost—machine utilization greater than 90%, multi-machine staffing, reduced inventory, and reduced floor space. • Delivery—complete machined wing rib, start to finish, in 1 to 2 days; single-piece production runs. The wing ribs are massive, measuring as large as 3.1 x 2 m. They are single-piece parts machined from an individual billet of a new, weight-saving, high-tensile-strength aluminum alloy. The project team decided to use a single-spindle machine over a multispindle gantry machine, which offered the advantage of dramatically fewer process variables to control. The spindle would need to be three times as efficient at removing metal as the alternative. Greater spindle utilization was also a must. The spindle was to have only one set of tools, one fixture, and a constant spindle interface. Airbus already was using highspeed horizontal machines for some of its wing rib production. The company determined that the horizontal machining approach was the only way to proceed when they would be making this quantity of chips. “You cannot afford for the parts to be lost under a sea of chips,” said Harland. Given this analysis, Airbus established stringent specifications for an automated wing rib machining cell, and eventually chose Makino’s. The company’s MAG4 equipment also includes an automated pallet-handling system. The company’s pallet-handling system included an area for the storage of six pallets and a 90° pallet tilt station, enabling parts to be loaded/unloaded on a horizontal surface and tilted vertically to present the parts to the horizontal spindles of the MAG-Series machines. Makino completed installation of its European demonstration MAG4 machine at the Airbus facility by March 2002. This enabled Airbus to immediately start the part process development activities on these new parts while the MAG4 machines for the system configuration were being produced. By September 2002, installation of the two production MAG-Series machines and the automatic pallet-handling system was complete. Production began shortly afterward. According to Makino, Airbus is achieving metal removal rates 2.6 times greater with the single-spindle than can be achieved on multi-spindle gantry machines. Makino believes the machine will surpass three-times capability, as specified. The ribs are being produced in a three-operation sequence on the MAG4. The first operation requires that the first side of the rib be roughmachined. The rib is then flipped over for the same process. After it is relaxed, the piece is finish-machined on the second side during the second step. The rib is next flipped back over to the first side and finish-machined. The throughput time from start to finish for machining a wing rib is one to two days, depending on the specific wing rib part being produced. The wing ribs are being run in single-piece production quantities, For the A380, Airbus made significant changes to its plant in Filton, UK, developing an advanced wing rib manufacturing cell using Makino equipment. 26 Aerospace Engineering October 2003 Tech focus dramatically reducing inventory levels. The raw material cost of each rib exceeds 15,000 euros (approximately $16,000). Only minimal staffing increases were required for the wing rib production facility to support the additional A380 machining requirements. This is due to the multi-machine staffing capability of the Makino Machining Complex automatic palletmm with a tolerance of –0.08 mm/ +0.25 mm. “We feel that the Makino machines can allow us to reduce to 0.8 mm with proven process capability,” he said. The Airbus A380 super jumbo jet is intended to achieve a 25% reduction in cost per seat and a 15% improvement in fuel efficiency. Patrick Ponticel handling system. Two operators are capable of loading and unloading the parts, with the Makino cell control software managing the machine scheduling, the indexing of the pallets to the machine, and the loading/ unloading station. Airbus is holding tolerances of ±0.095 mm on the extremities of its parts, according to Harland. This is done with pocket thicknesses of 1.1 Drilling, installation of fasteners leaned out at Boeing A new drill/insert fastener end effector developed by J.F. Hubert Enterprises, Brown Aerospace, and Boeing is a good example of lean manufacturing, eliminating as it does several steps between hole drilling and fastener installing. The device is being used in an aircraft fuselage for drilling an aluminum stack-up of aluminum/ aluminum and aluminum-titanium bulkheads. Most hols are 3/16- or 1/4-in diameter with controlled-depth countersinks. Capability requirements of the end effector include: • Burr-free drilling. • Wet drilling (faying surface seal present between skin and substructure while drilling). • Countersink depth control on single bit for one-up, one-pass (burrless) operation. • Interference-fit fastener insertion of a Hi-Lok fastener in the current process. (Freedom to transition to a Monogram OSI one-sided fastener is designed-in with a rapid change-out module.) The technology eliminates more than half the steps previously required, including manual deburring, and generates “huge savings,” according to the companies. Crimping tool from Tyco is lightweight affair Tyco’s micropneumatic crimping tool with tool holders and crimp heads. A micro-pneumatic crimping tool from Tyco Electronics that measures 5.75 in long and has a mass of 1.5 lb is 50% smaller and 35% lighter than the company’s widely used 6-26 pneumatic hand tool (it is not designed as a replacement for the 6-26), allowing for use in more ergonomically challenging operations. Its small size and negligible weight are well suited for intricate crimping processes found in airframe wiring installation and repair situations. Hand-actuated, it operates on air pressure of 90 psi. The power unit is compatible with the small tool holder and adapters used on the 6-26 unit. When used with compatible crimping heads, it will typically crimp terminals and splices to 26-14 AWG wire. In some cases, as with AMP SOLISTRAND terminals, the acceptable wire range is 22-10 AWG. The tool can be outfitted with a double-action crimp head, a T-HEAD crimper, or a straight-action crimp head. It is designed to crimp many types of terminals, splices, and contacts including PLASTI-GRIP butt splices and terminals, PIDG terminals and splices, SOLISTRAND uninsulated terminals and splices, AMPLIMITE size 20 and DF contacts, as well as circular plastic connector contacts and MATE-N-LOK contacts. Micro-pneumatic hand tools are general-purpose tools designed for intermediate production volumes that require more speed than unpowered hand tools, but do not demand the capacity of a semi-automatic bench press. Patrick Ponticel Aerospace Engineering October 2003 27 Tech focus Here are the steps in the previous process: 1. Apply doublers on top of the bulkheads. 2. Apply skins over the doublers. 3. Drill 7000 holes through the skin using an automated drillonly machine. 4. Cleco every fourth hole in the skin. 5. Take out all 1750 clecos at completion of drilling. 6. Separate the layers and hand deburr the three sets of skins and the doublers. 7. Manually deburr OML (outside mold line) side of the three sets of skins. 8. Manually deburr IML (inside mold line) side of the three sets of skins. 9. Manually deburr doublers on both sides. 10. Prepare and seal the bulkheads (the skins are not present). 11. Apply the doubler and seal again. 12. Apply skins back onto aircraft substructure. 13. Hand-insert the Hi-Lok fasteners. The new process, which requires 50% fewer crane moves, is as follows: 1. Prepare the bulkheads by applying the faying surface seal. 2. Attach the doubler and apply seal for the doubler. 3. Locate the aircraft skins onto the substructure. 4. Drill and install fastener in oneup, one-pass fashion. With a reduction in setups and adjustments, the new process involves less manual interaction, less idling, and fewer minor stoppages, the companies say. Patrick Ponticel The Brown Aerospace DIFF end effector is shown with the cover open (left) and with the cover closed. Shown are the center barrel gantry automated fastening machine and C17 Globe Master III bottom barrel inverted for the skinning process. Quenching a thirst for better heat treating IQ Technologies Inc.’s IntensiQuench process for steel parts can best be described as a water-quenching method resulting in an optimized level and depth of compressive surface stressed with acceptable part distortion in a throughhardened part. The process was “discovered” by Nikolai Kobasko, Director of Technology at IQ. He sought an alternative heat-treatment method for hardening steel parts through the use of pure water quenchant or low-concentration water/salt solutions. The generally accepted cooling liquid had been oil, making heat treating occasionally hazardous and environmentally unfriendly. Prevailing wisdom has been that only a slow quench could limit distortion or cracking of metal parts, and that water could not cool the metal evenly enough to avoid distortion 28 Aerospace Engineering October 2003 Tech focus to either the surface or deep within the metal. But what Kobasko found is that pure water or a water/salt solution intensely agitated (at a rate several hundred times that used for conventional oil quenching) kept distortion to a minimum, provided that it was interrupted at the point of maximum compressive surface stresses. A team led by Kobasko found that very fast and uniform part cooling actually reduced part cracking and distortion while improving surface hardness, depth of hardness, and durability of steel parts. In addition, the process allowed for the use of less alloy steel, resulting in parts that can be made lighter but stronger and more cost effective. IQ has since developed computer models for intensive quenching that project the optimal time for interruption. Patrick Ponticel The first production furnace in the U.S. using the IntensiQuench process is owned by Euclid Heat Treating Co. Measurement time cut in half with new bore gage The only family owned aircraft manufacturer in the U.S., Schweizer Aircraft Corp. is using an electronic bore gage from Fowler/Bowers to make parts inspection more efficient and reliable. The maker of helicopters, agricultural and reconnaissance aircraft, and special-purpose unmanned vehicles, Schweizer (also a subcontractor to Boeing, Northrup-Grumman, Sikorsky, and Lockheed-Martin) is giving closer attention to upgrading its in-processing inspection operations, particularly those that can be performed directly on the production floor by manufacturing personnel. “We need instruments that can help us to continually produce parts of known value,” said Jeff Waters, Inspection Manager at the 400-person company. The bore gage from Fowler/ Bowers has helped Schweizer halve the time it takes to check tolerances of as little as 0.0005 in for the many precision-machined products it manufactures. “The company formerly relied on vernier-type inside micrometers for this assessment program, but we found inconsistent results,” Waters said. “With the Fowler/Bowers Holematic Mark II gage, all anyone using the instrument has to do is insert the probe into the bore, squeeze the trigger, and get the reading quickly.” The pistol-grip gage has a resolution of 0.00005 in and a large, easy-toread LCD swivel display as well as two pre-set memories. Heads above 0.5-in diameter are fitted with tungsten-carbide measuring anvils. Special anvils are used for threads, splines, and slots. As part of its efforts to improve inspection efficiency, Schweizer is moving into use of coordinate measuring machines and has upgraded its tooling with the addition of highaccuracy Sumitomo drills, according to Rick Kent, Schweizer Production Manager. He said the company recently has added a portable articulating arm to measure airframes. Kent said gage calibration is carried out at least every six months. Patrick Ponticel A Fowler/Bowers pistol-grip bore gage is used to check a Schweizer Aircraft Corp. helicopter idler pulley. |
|