Patent Application
20090033013
The invention relates generally to a lay-up mandrel assembly for a one-piece barrel fuselage, and more particularly to a lay-up mandrel assembly for a one-piece barrel fuselage having an automated clamping and indexing system.
Automated Fiber Placement (AFP) mandrels are used in the aerospace industry to assist in the formation of parts used in building aircraft, such as composite materials. Barrel-shaped components, such as fuselage skins and stringers, are typically laid up on mandrels composed of multiple rigid segments during manufacturing of the barrel-shaped components. During the manufacturing process, the barrel-shaped component laid up on the mandrel undergoes a curing process, typically performed in an autoclave in order to set the shape of the component part. Once cured, the mandrel segments are then dismantled and separated from the part being manufactured in order to remove the barrel structure from the mandrel. In the industry, there is a need to have a way to affix these mandrel segments together in order to form the proper tooling for construction of aircraft parts.
In the past, the aerospace industry would typically affix and detach these mandrel segments by bolting and unbolting the mandrel segments. However, this process is not desirable because it is not ver robust, and the bolting process requires a great deal of time to perform which slows down the production process for forming the barrel-shaped components for use in aircraft. The mandrel segments, particularly when bolted together, may require large handling equipment to assist mechanics with the assemble/disassemble process. Further, by using bolts, sometimes personnel are required to climb inside the mandrel to unfasten bolts and guide the equipment as described in U.S. Pat. No. 7,166,251 which is assigned to The Boeing Company. The process of bolting, unbolting and re-bolting segments in the assembly line also may not be flexible and lean enough for use in certain manufacturing applications.
Clamping mechanisms sometimes may be used in place of bolting mechanisms. These prior an clamping designs possessed mechanical means to lock and unlock, and these clamps also included a large bar running through the mandrels that actuated back and forth to engage and disengage the clamps. Clamping or bolting the mandrel segments using the above-described approaches can be very time consuming and prone to human error. The assembly method of the mandrel does not make manual bolting or clamping desirable due to the limited amount of space available. The factory flow requirements of the mandrel assembly does not lend itself to manual clamping or bolting, and therefore there is a need for a faster automated method to be established that would ensure not only precise location of the mandrel segments but also ensure that the joint is securely fastened.
Indexing is a process to locate in a precise manner how the mandrel segments are positioned with respect to each other. A typical mechanism utilized for indexing is called a cup and cone configuration wherein the cup and cone are aligned between the mandrel segments to be affixed together such that the mandrel segments may be properly positioned in order to support the aircraft part during the manufacturing process. While indexing via a cup and cone configuration generally results in accurate alignment of the mandrel segments, there is a need to integrate an indexing mechanism with a mechanism utilized for fastening the mandrel segments together so as to ensure alignment and secure fastening of the mandrel segments.
An embodiment of the present invention is directed to an integrated clamping and indexing system comprising a clamp body, a clamp arm eccentrically mounted to the clamp body and having a hooklike structure, and a clamp index attached to said clamp body wherein the clamp index performs indexing simultaneously with clamping upon actuation of the clamp arm. This integrated clamping and indexing system also preferably is comprised of a clamp receiver integrated with a receiver index wherein the clamp receiver locks into position with the clamp arm, and the receiver index contacts with the clamp index when the clamp arm is actuated. This system, according to embodiments of the present invention, may be used to join mandrel segments and additionally or alternatively may be used to join mandrel segments to end rings. The system further provides that face-sheets of the mandrel segments align and contact with each other when the clamp arm is actuated.
Another embodiment of the present invention is directed to a method for integrated clamping and indexing comprising exerting pull-up force on a clamp arm, actuating the clamp arm such that the clamp arm affixes to a clamp receiver, and pulling down a clamp index integrated with the clamp arm, wherein the clamp index contacts with a receiver index integrated with the clamp receiver upon actuation of the clamp arm. The pull-tip force preferably moves the clamp arm in an eccentric manner to lock in place with the clamp receiver. Further embodiments provide that the clamp index has a cup-like configuration and the receiver index has a cone-like configuration. The indexing mechanism formed by the clamp index and the receiver index preferably guides the clamp arm into place relative to the clamp receiver.
In a further embodiment of the present invention, a mandrel clamp and index assembly is provided wherein the assembly comprises a clamp body, clamp arms integrated with the clamp body, and a clamp cone index integrated with the clamp body. Upon actuation of the clamp arms, the clamp cone index makes contact with a receiver index to guide the clamp arms to lock in place with a clamp receiver. The clamp receiver preferably affixes to the clamp arms by a pulling-up motion upon actuation of the clamp arms. Further embodiments of the assembly include a clamp mounting pan which provides a support for mounting clamp brackets which support the clamp arms.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.
For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
Embodiments of the present invention provide a multi-piece automated fiber placement mandrel clamping and indexing mechanism wherein a clamping mechanism is used in order to secure mandrel segments together as well as to join mandrel segments to end rings. The clamping mechanism is preferably integrated with the mandrel, and the clamping mechanism provides an increased clamping force in order to more fully support and fasten the mandrel segments in an automated manner. The clamping and indexing mechanism of the present invention can preferably withstand the autoclave heat and pressure that is typically experienced during the curing, part of the manufacturing process. The clamping mechanism is also integrated with an indexing mechanism according to embodiments of the present invention such that mandrel segments will preferably remain securely connected and aligned until air is applied to the clamping and indexing assembly in order to unclamp the mandrel segments and remove the part being manufactured.
Clamp body 212 preferably includes clamp arm(s) 202 that preferably clamp to clamp receiver 213. Clamp arm 202, according to an embodiment of the present invention, is air-actuated such that clamping and indexing mechanism 20 may be more easily incorporated and packaged into mandrels. Clamp arm 202 preferably incorporates an eccentric over-center locking mechanism; accordingly, once the air required to lock clamp arm 202 into position is removed, clamp arm 202 will remain locked and indexed until air is again applied to unclamp. Clamp arm 202 preferably has a hook-like shape that can pull-tip onto clamp receiver 213 to more easily lock clamp arm 202 into place with clamp receiver 213. Preferably clamp arm 202 joins mandrel segments to each other and also may preferably join mandrel segments to end rings. The shape and mounting of clamp arm 202 provides for more pull-up force. Preferably the eccentric lever arm radius of clamp arm 202 is approximately 0.250 inches having a minimum pull-up force of approximately 1500 pounds and a maximum pull-up force of approximately 4000 pounds.
Clamp index 203 is of a preferred size and shape to affix to receiver index 201 when clamp arm 202 is actuated. Clamp index 203 is integrated with clamp body 212 such that clamping and indexing of the mandrel segments preferably occurs in an integrated and simultaneous manner. Clamp index 203 and receiver index 201 are preferably formed in a cup and cone configuration to index and locate clamp arm 202 in a desired position relative to clamp receiver 213. The use of a cup and cone indexing mechanism is a common way to locate surfaces to one another; however, the present invention integrates this cup and cone indexing mechanism with a clamping mechanism. Clamp receiver 213 is mounted to clamp receiver mounting plate 205 which is flush against mandrel substructure 204. Receiver index 201 also is affixed to clamp receiver 213 such that when clamping occurs, the indexing of the assembly occurs in an integrated manner along with the clamping mechanism as will be described in more detail below.
Clamp receiver 213 and receiver index 201 are preferably incorporated into the indexing and clamping mechanism of the present invention so as to encourage even distribution of the clamping forces during actuation as well as to permit some variation in the initial pre-clamp location or positioning. Clamp receiver 213 permits clamp arm 202 to tightly connect with clamp receiver 213 such that the mandrel segments may be tightly locked together. Receiver index 201 preferably connects with clamp index 203 which is integrated with clamp body 212 of the clamping mechanism such that the clamping and indexing mechanism guides the mandrel segments into the required position. Thus, the desired clamp force may be applied while pulling the mandrel segments into the proper location and position.
Mandrel face sheets 207, 208 preferably contact with one another when clamp arm 202 is actuated. Mandrel seal grooves 209 become flush with mandrel face sheet 208 when the clamping and indexing mechanism according to embodiments of the present invention is engaged. Mandrel extraction path 206 indicates the manner in which the mandrel becomes attached to and detached from the clamping and indexing mechanism according to embodiments of the present invention.
When clamp arm 202 is actuated, clamp index 203D having a cup-like configuration and integrated with clamp body 212 pulls down to cover receiver index 201 wherein receiver index 201 is formed in a cone-like configuration. The integrated nature of clamp body 212 and clamp index 203 preferably allows for clamp index 203 and receiver index 201 to become flush with one another so as to assist in locating the clamping mechanism in the desired position for locking the mandrel segments into their preferred placement for use in manufacturing a barrel-shaped component. When clamp arm 202 is actuated and locked into place with clamp receiver 213, mandrel face sheets 207, 208 make contact such that seal grooves 209 are compressed with face sheet 208 to form a tight seal between mandrel face sheets 207, 208 during manufacturing.
Embodiments of the present invention utilizing a mechanism for integrated clamping and indexing of the mandrel segments and end rings provide improvements over the prior art bolting and clamping mechanisms. While clamping mechanisms may have been used in the past for fastening parts together, the present invention provides a novel means for integrating a clamping mechanism with an indexing mechanism in order to attach, through an automated process, the mandrel segments and end rings in a secure and accurately aligned manner, such that a tight seal may be formed between the mandrel segments and/or end rings during a manufacturing process. The clamping mechanism according to embodiments of the present invention is modified so as to increase the clamping force exerted by the clamping mechanism in order to more fully support the mandrel segments in an automated manner. Preferably no secondary locking mechanism is needed when the clamping mechanism of the present invention is utilized as the locking mechanism is integrated into the clamping mechanism. As a tight seal is formed between the mandrel segments when the clamping and indexing mechanism of the present invention is utilized, this mechanism provides the advantage that the formed mandrel can withstand autoclave heat and pressure without breaking the seal between the respective mandrel segments and/or end rings.
Mandrel segments locked into position utilizing the clamping and indexing mechanism according to embodiments of the present invention were tested into the autoclave environment during a curing cycle. In order to conduct such tests, fiberglass was applied to the exterior of the locked mandrel segments, and the locked mandrel segments were run in the autoclave through a cure cycle. When the cure cycle was completed, the locked mandrel segments were removed and inspected. The mandrel segments locked together using the clamping and indexing mechanism of the present invention possessed good laminates so as to confirm no leaks had occurred in the mandrel. Other testing of the locked mandrel segments was performed using mandrel manipulators, and the results confirmed that the seals worked properly. According to embodiments of the present invention, when the locked mandrel segments are autoclaved and cured, the formed mandrel remains in its original shape and does not collapse or otherwise become deformed. Accordingly, the shape and positioning of the part being formed using the locked mandrel segments may be maintained.
Embodiments of the clamping and indexing mechanism of the present invention passively lock the mandrel segments together in a secure manner. The clamping and indexing mechanism preferably meets clamp-up travel needs and all known capacity needs. The clamping and indexing mechanism further successfully packages in available space using predominantly off-the-shelf clamp hardware. While back-up provisions, such as bolting mechanisms, may be available for holding the mandrel segments together, these back-up provisions typically do not need to be used as the clamping and indexing mechanism of the present invention maintains the mandrel segments aligned and in the desired locked position for use in manufacturing processes without damaging the mandrel or the part being formed using the mandrel.
Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
