Search Results

Accurately measuring the length of a pintail type fastener is limited by the process of forming the fastener. When the pintail is formed its overall length is not dimensionally controlled. To accurately measure the grip of the bolt a vision system is utilized that finds the notch between the tail and bolt shank. The grip, diameter, and angle of the bolt prior to insertion are then measured. This method proves to be more accurate than measuring the bolt mechanically and provides a number of other advantages including; decreased measurement time, improved accuracy, FOD detection, and angle of the bolt in the fingers prior to insertion.

In an attempt to be more flexible and cost effective, Aerospace Manufacturers have increasingly chosen to adapt a manufacturing style which borrows heavily from the Automotive industry. To facilitate this change in methodologies a system for locating robots has been developed which utilizes cameras for both locating and guidance of a mobile platform for a robot with drilling and fastening end effector.

A new style of rivet injector is in production use on a variety of fastening machines used by major aircraft manufacturers. In this injector the opposing sides of the rivet guide blocks are attached to the arms of a parallel gripper. We have implemented the parallel gripper in both vertical axis and horizontal axis riveting applications. It is equally effective in both orientations. We have implemented the parallel gripper rivet injector on headed rivets, threaded bolts, ribbed swage bolts and unheaded (slug) rivets.

Electroimpact has designed the E6000, the next generation riveting machine, with a focus on reduced weight and speed. It will initially be used on ARJ21 wing panels in Xi'an, China, but it is able to fasten a variety of panels including A320 and 737. The E6000's fastening cycle is capable of forming and shaving 16 rivets per minute. Head alignment is maintained by two independent four axis heads using a combination of controls and kinematics. Process tool speed has been improved via high lead screws, high speed Fanuc motors, and a shorter head stone drop. An innovative EI operator interface enhances end user experience.

Electroimpact has developed an automated solution for installing OSI-Bolts on the HStab for Boeing's 787-9 aircraft. This solution utilizes Electroimpact's existing accurate robotic system together with new hardware designed specifically for OSI-Bolts. In addition to automated drilling and fastener installation, this system performs numerous quality checks to insure the installed fastener meets engineering requirements. Before installing the fastener, the system measures actual stack thickness and the length of the fastener to ensure that the proper grip is installed. Torque and angle feedback are recorded during installation which can be used determine if the fastener was installed correctly. The system will also automatically shave the small protuberance on the fastener head left by the broken off fastener stem, which is inherent to the OSI-Bolt. Figure 1 Cell Overview

Electroimpact has developed a novel method for accurately drilling and countersinking holes on highly convex parts using an articulated arm robotic drilling system. Highly curved parts, such as the leading edge of an aircraft wing, present numerous challenges when attempting to drill normal to the part surface and produce tight tolerance countersinks. Electroipmact's Accurate Robot technology allows extremely accurate positioning of the tool point and the spindle vector orientation. However, due to the high local curvature of the part, even a small positional deviation of the tool point can result in a significantly different normal vector than expected from an NC program. An off-normal hole will result in an out of tolerance countersink and a non-flush fastener.

The E7000 riveting machine installs NAS1097KE5-5.5 rivets into A320 Section 18 fuselage side panels. For the thinnest stacks where the panel skin is under 2mm (2024) and the stringer is under 2mm (7075), the normal process of riveting will cause deformation of the panel or dimpling. The authors found a solution to this problem by forming the rivet with the upper pressure foot extended, and it has been tested and approved for production.

Electroimpact's newest riveting machine features a track-style injector with Bomb Bay Ejection Doors. The Bomb Bay Ejection Doors are a robust way to eject fasteners from track style injector. Track style injectors are commonly used by Electroimpact and others in the industry. Using the Bomb Bay Doors for fastener ejection consists of opening the tracks allowing very solid clearing of an injector when ejecting a fastener translating to a more reliable fastener delivery system. Examples of when fastener ejection is needed are when a fastener is sent backwards, when there are two in the tube, or when a machine operator stops or resets the machine during a fastening cycle. This method allows fasteners to be cleared in nearly every situation when ejecting a fastener is required. Additional feature of Electroimpact's new injection system is integrated anvil tool change.

Boeing has relied upon the 767 ASAT (ASAT1) since 1983 to fasten the chords, stiffeners and rib posts to the web of the four 767 wing spars. The machine was originally commissioned with a Terra five axis CNC control. The Terra company went out of business and the controls were replaced with a custom DOS application in 1990. These are now hard to support so Boeing solicited proposals. Electroimpact proposed to retrofit with a Fanuc 31I CNC, and in addition, to replace all associated sensors, cables and feedback systems. This work is now complete on two of the four machines. Both left front and right front are in production with the new CNC control.

The newest generation of automated fastening machines require a feed system that is smaller, more flexible, and faster than any currently available. The feed system must be compact enough to fit on a robot base, yet have a capacity large enough to support unmanned production for hours. A large variety of fasteners must be supported and the entire system must be reloaded or reconfigured in minutes to match the next work piece being assembled by the machine. When requested by the part program, the correct fastener must be released directly and immediately into the feed tube to minimize cycle time. This paper describes a new “plate cartridge” feed system developed to meet these needs.

Manufacturing C cross-sectional components with high aspect ratios out of carbon fiber reinforced composites is desirable by the aircraft industry. Modular AFP heads with short, fixed tow path have the fundamental performance characteristics required to successfully and productively automate the production of these part families. Aircraft parts in this family include wing spars, stringers, and fuselage frames.

The use of a narrow profile posts or Skinny Fixture increases build speed and flexibility while improving quality of aluminum aircraft panels fastened in one-up assembly cells. Aluminum aircraft panels are made up of an outer skin and a series of stringers. The components must be held in accurate relative positions while preliminary fasteners are installed. By using narrow fixture posts in conjunction with deep drop stringer side machine tools, the fastening machine can apply fasteners at tighter initial spacing. The spacing is gained by providing clearances that allows the centerline of the fastening system to work closer to the post than previously achieved with deep fixture posts and short stringer side tooling. At one time the standard process was to hold the parts in manual tack cells and after tacking the panels are moved to a separate automated fastening cell. One-up assembly fixtures improve the process by reducing manual processes while minimizing component handling.

There is an ever-present risk for the lower ram on a riveting machine to suffer a damaging collision with aircraft parts during automated fastening processes. The risk intensifies when part frame geometry is complex and fastener locations are close to part features. The lower anvil must be led through an obstructive environment, and there is need for crash protection during side-to-side and lowering motion. An additional requirement is stripping bolt collars using the downward motion of the lower ram, which can require as much as 2500 pounds of pulling force. The retention force on the lower anvil would therefore need to be in excess of 2500 pounds. To accomplish this a CNC controlled electromagnetic interface was developed, capable of pulling with 0-3400 pounds. This electromagnetic safety base releases when impact occurs from the sides or during downward motion (5 sided crash protection), and it retains all riveting and bolting functionality.

Automated collar and nut installation requires complex hardware on the wet side of the spar or wing panel. Wet side automatic tool changers are becoming common but an operator is often required to connect electrical, pneumatic and fastener feed system components. This is unacceptable in a lights-out cell, and any fully automatic solution must be reliable while satisfying demanding design requirements. Figure 1 Wet side anvil for nut installation. The 737 Spar Assembly Line (SAL) is a new lights-out machine cell at the Boeing factory in Renton, Washington. The SAL machines are equipped with a unique fully automatic tool changer (ATC). The wet side ATC interface is designed to automatically connect conventional as well as more unique services such as fastener feed. The fastener feed ATC module, called the “spinner,” rotates with the machine’s wet side rotary axis (C axis). It consists of a stack of rotors that rotate inside of a stationary annulus.

Growing use of composite materials in aircraft wing construction requires a new generation of drilling machines. Electroimpact's new LTD drilling machine features a Bolt Injector with improvements for more streamlined operation and less operator intervention. The Bolt Injector “injects” or stages Single Sided Temporary Fasteners (SSTF). It features hands-free automated tool change between three different feed paths for a total of eight different fastener diameters being fed through one set of Bolt Injector hardware. This is accomplished with an indexing system for three feed tubes fed to the machine head, with each feed tube serving more than one diameter. Furthermore the LTD Bolt Injector checks fastener diameter at the machine head and also length in conjunction with Bolt Inserter servo axis. The bolt diameter is checked with an analog sensor attached to a gripping mechanism. The length check is accomplished with a “touch off” pad and the Inserter's servo motor encoder.

A simple, open, post and index system is used for final alignment and joining of the fuselage and wings of a new passenger business jet. 19 manually actuated axes precisely move the wings, forward, and rear fuselage sections into position. Movement is accomplished with industrial jacking screws and positions recorded with precision linear potentiometers. Wing sweep, angle of attack, and dihedral are monitored and controlled. The axes positions are downloaded to data files for verification and data archiving. The Gulfstream G150 Join Cell's open architecture enhances access to fasten the main aircraft structure while maintaining flight critical geometry.

A new high speed forming process for fatigue rated index head rivets used in wing panel assembly using ball-screw based servo squeeze actuation has been developed. The new process is achieved using a combination of force and position control and is capable of forming to 40,000 lbs at rates of up to 200,000 lbs/second whilst holding the part location to within +/− 10 thousandths of an inch. Multi-axis riveting machines often have positioning axes that are also used for fastener upset. It is often the case that while a CNC is used for positioning control, another secondary controller is used to perform the fastener upset. In the new process, it has been possible to combine the control of the upset process with the machine CNC, thus eliminating any separate controllers. The fastener upset force profile is controlled throughout the forming of the rivet by using a closed loop force control system that has a load cell mounted directly behind the stringer side forming tool.

Since Automated Fiber Placement (AFP) is used to manufacture twin-aisled commercial aircraft parts, extremely large envelope machines are often required and appropriate. Additionally, for very large parts, the average AFP course length may be on the order of one to two meters, and the part may have numerous contours. With courses of this length, a high acceleration machine is necessary to achieve fast laydown rates because the machine is frequently starting and stopping. Part contour also requires high acceleration machine axes to accurately maintain the AFP tow path at high feedrates. Large machines with high accelerations result in very large loads on bearings. Large loads and the long, high speed axis travels associated with large envelope machines make achieving a long service life difficult. Designing efficient, lightweight machine structures becomes critical to provide long machine service life.

Starting in 2003 Electroimpact began development on a comprehensive kinematic and compensation software package for machines with large envelopes. The software was first implemented on Electroimpact's Automatic Fiber Placement (AFP) equipment. Implementation became almost universal by 2005. By systematically collecting tracker measurements at various machine poses and then using this software to optimize the kinematic parameters of the machine, we are able to reliably achieve machine positional accuracy of approximately 2x the uncertainty of the measurements themselves. The goal of this paper is to document some of the features of this system and show the results of compensation in the hope that this method of machine compensation or similar versions will become mainstream.

Electroimpact has produced a new in-process inspection system for use on drilling and fastening systems. The system uses a high-accuracy, non-contact, laser system to measure the flushness of installed fasteners. The system is also capable of measuring part normality and providing feedback to the machine for correction. One drawback to many automatic inspection systems is measurement error. Many sources of measurement error exist in a production environment, including drilling chips, lubrication, and fastener head markings. Electroimpact’s latest system can create a visualization of the measured fastener for the operator to interpret. This allows the operator to determine the cause of a failed measurement, thus reducing machine downtime due to false negatives. Electroimpact created a custom C# WPF application that queries the point-cloud data and analyzes the raw data. A custom “circle Hough transform” scoring algorithm is used to find the center of the nosepiece (pressure foot).