EP2804720A1

EP2804720A1 - Low force temporary fastener

Info

Publication number: EP2804720A1
Application number: EP12701627.7A
Authority: EP
Inventors: Stephan Joel FAVILLA; Alan Ray Merkley
Original assignee: Boeing Co
Current assignee: Boeing Co
Priority date: 2012-01-17
Filing date: 2012-01-17
Publication date: 2014-11-26
Anticipated expiration: 2032-01-17
Also published as: WO2013109251A1; EP2804720B1

Abstract

An apparatus for clamping a work piece at a maximum force may include a body, a rod, a cap, a biasing mechanism, and a pair of tangs. A first end of the body may be configured to engage a first surface of the work piece. The rod may be configured to move along the axial length of the body. Rotating the cap may cause the cap to move axially along the rod along threads. A biasing mechanism may be connected to the rod such that axial movement of the rod beyond a desired point may engage the biasing mechanism. Rotation of the cap may be configured to compress the biasing mechanism. The tangs may be configured to engage a second surface of the work piece at a desired level of force at different levels of extension of the tangs and rod.

Description

LOW FORCE TEMPORARY FASTENER

BACKGROUND INFORMATION

Field:

The present disclosure relates generally to clamping and, more particularly, the present disclosure relates to methods and apparatuses for clamping parts together with a maximum force. Still more particularly, the present disclosure relates to clamping parts, such as aircraft components, temporarily with a maximum force.

Background:

Manufacturing and assembly of structures, such as those for aircraft, may involve the assembly of different parts to form the structures. Different parts and/or structures may be connected to each other in manufacturing the aircraft. Structures such as skins, plies, reinforcing ribs, stringers, and/or other suitable structures may be used to support other parts and/or structures in the aircraft.

During the assembly of structures, it may also be desirable to temporarily join components together. For example, a skin being attached to a rib of an aircraft may be temporarily attached to the rib. During the temporary attachment, further assembly operations may take place. For example, the parts may be more permanently aligned. Additionally, permanent fastener holes may be bored or formed in the parts. As a further example, shims or spacers may be positioned between the temporarily joined parts so as to achieve a desired spacing between the parts. Other operations may also take place while two or more parts may be temporarily joined together.

A certain level of fit between parts may be desired but not always possible. For example, during manufacture of an aircraft wing assembly, the skin of a wing may be attached to a spar of the aircraft frame. The skin and spar may be examples of adjacent pieces that may benefit from the use of a shim. A shim may be placed in the space between adjacent parts. In certain cases, placement of the shim may be assisted by temporarily joining the parts together.

It may be desired to use a clamping device to temporarily join parts together. In the aviation industry, various kinds of clamps may be used. It would be desired not to harm the surfaces of the materials being assembled by using too large a clamping force. However, current clamping devices may not offer a quick means of temporarily clamping and unclamping a work piece with a force of a desired moderate force so as to assure an operator that damage to a work piece surface does not result from the clamping.

Current devices may also provide a variable clamping force which is determined by factors such as the size or thickness of a work piece. A clamp may provide a first clamping force for a work piece that is relatively thin, and the clamp may provide a second, different clamping force for a work piece that is relatively thicker. This kind of variable clamping force that depends on the size or thickness of the work piece may not be suitable for some needs.

As a result, the manufacturing and assembly of an aircraft may take more time and expense than desired to obtain a desired positioning of parts during temporary clamping. Additionally, using known methods, parts that are temporarily fastened together may be subject to too much force. Accordingly, it would be desirable to have a method and apparatus that takes into account one or more of the issues discussed above, as well as possibly other issues.

SUMMARY

An illustrative embodiment of the present disclosure may provide a clamp that includes a body, a fastener system, and a biasing mechanism. The body may include an interior region and a first end configured to contact a first surface of a work piece. The fastener system may be configured to move axially within the interior region of the body and through a hole in the work piece to a second surface of the work piece in which the fastener system has a second end configured to engage the second surface of the work piece. The biasing mechanism may be connected to the fastener system. The biasing mechanism may be configured to apply a force on the fastener system to cause the second end of the fastener system and the body to engage the work piece at a desired level of force at different levels of extension of the fastener system.

A further illustrative embodiment of the present disclosure may provide an apparatus for clamping a work piece at a maximum force. The apparatus may include a body, a rod, a cap, a biasing mechanism, and a pair of tangs. A first end of the body may be configured to engage a first surface of the work piece. The body may include an interior region, and the body may be characterized by an axial length. The rod may be positioned partially within the body. The rod may be configured to move along the axial length of the body and threading positioned on the rod. The cap may be threadedly attached to the rod such that rotating the cap may cause the cap to move axially along the rod. The biasing mechanism may be connected to the rod, the body, or the cap such that axial movement of the rod beyond a desired point may engage the biasing mechanism. Rotation of the cap may compress the biasing mechanism. The biasing mechanism may be configured to establish a clamping force. The pair of tangs may be connected to the rod and may be configured to transition between an extended position and a compressed position. The tangs may be configured to engage a second surface of the work piece.

Still a further illustrative embodiment of the present disclosure may provide a method for clamping a work piece at a desired force. The method may include steps of inserting a pair of tangs through a hole of the work piece; rotating a cap connected to a rod in a first direction such that the tangs engage a surface of the work piece; and compressing a biasing mechanism to establish a clamping force.

The features and functions can be achieved independently in various embodiments of the present disclosure or may be combined in yet other embodiments in which further details can be seen with reference to the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the illustrative embodiments are set forth in the appended claims. The illustrative embodiments, however, as well as a preferred mode of use, further objectives, and features thereof will best be understood by reference to the following detailed description of an illustrative embodiment of the present disclosure when read in conjunction with the accompanying drawings, wherein:

Figure 1 is an illustration of a block diagram of an aircraft manufacturing and service method in which an illustrative embodiment may be implemented;

Figure 2 is an illustration of a block diagram of an aircraft in accordance with an illustrative embodiment;

Figure 3 is an illustration of a block diagram of a clamping environment in accordance with an illustrative embodiment;

Figure 4 is an illustration of a diagram of a clamp in use with an aircraft in accordance with an illustrative embodiment;

Figure 5 is an illustration of a diagram of a clamp in accordance with an illustrative embodiment;

Figure 6 is an illustration of a cross-sectional diagram of a clamp minus the work piece in accordance with an illustrative embodiment;

Figure 7 is an illustration of a cross-sectional diagram of a clamp in accordance with an illustrative embodiment; Figure 8 is an illustration of a diagram of a clutch for use with a clamp in accordance with an illustrative embodiment;

Figure 9 is an illustration of a flowchart of a process for clamping a work piece in accordance with an illustrative embodiment; and

Figure 10 is an illustration of a flowchart of a process for unclamping a work piece in accordance with an illustrative embodiment.

DETAILED DESCRIPTION

Referring more particularly to the drawings, embodiments of the disclosure may be described in the context of aircraft manufacturing and service method 100 as shown in Figure 1 and aircraft 200 as shown in Figure 2. Turning first to Figure 1, an illustration of a block diagram of an aircraft manufacturing and service method is depicted in accordance with an illustrative embodiment. During pre-production, aircraft manufacturing and service method 100 may include specification and design 102 of aircraft 200 in Figure 2 and material procurement 104.

During production, component and subassembly manufacturing 106 and system integration 108 of aircraft 200 in Figure 2 may take place. Thereafter, aircraft 200 in Figure 2 may go through certification and delivery 110 in order to be placed in service 112. While in service 112 by a customer, aircraft 200 in Figure 2 may be scheduled for routine maintenance and service 114, which may include modification, reconfiguration, refurbishment, and other maintenance or service.

Each of the processes of aircraft manufacturing and service method 100 may be performed or carried out by a system integrator, a third party, and/or an operator. In these examples, the operator may be a customer. For the purposes of this description, a system integrator may include, without limitation, any number of aircraft manufacturers and major- system subcontractors; a third party may include, without limitation, any number of vendors, subcontractors, and suppliers; and an operator may be an airline, a leasing company, a military entity, a service organization, and so on.

With reference now to Figure 2, an illustration of a block diagram of an aircraft is depicted in which an illustrative embodiment may be implemented. In this example, aircraft 200 may be produced by aircraft manufacturing and service method 100 in Figure 1 and may include airframe 202 with plurality of systems 204 and interior 206. Examples of systems 204 may include one or more of propulsion system 208, electrical system 210, hydraulic system 212, and environmental system 214. Any number of other systems may be included. Although an aerospace example is shown, different illustrative embodiments may be applied to other industries, such as the automotive industry.

Apparatuses and methods embodied herein may be employed during at least one of the stages of aircraft manufacturing and service method 100 in Figure 1. As used herein, the phrase "at least one of, when used with a list of items, means that different combinations of one or more of the listed items may be used and only one of each item in the list may be needed. For example, "at least one of item A, item B, and item C" may include, for example, without limitation, item A, or item A and item B. This example also may include item A, item B, and item C or item B and item C.

In one illustrative example, components or subassemblies produced in component and subassembly manufacturing 106 in Figure 1 may be fabricated or manufactured in a manner similar to components or subassemblies produced while aircraft 200 is in service 112 in Figure 1. As yet another example, a number of apparatus embodiments, method embodiments, or a combination thereof may be utilized during production stages, such as component and subassembly manufacturing 106 and system integration 108 in Figure 1. "A number", when referring to items, means one or more items. For example, a number of apparatus embodiments may be one or more apparatus embodiments. A number of apparatus embodiments, method embodiments, or a combination thereof may be utilized while aircraft 200 is in service 112 and/or during maintenance and service 114 in Figure 1. The use of a number of the different illustrative embodiments may substantially expedite the assembly of and/or reduce the cost of aircraft 200.

For example, one or more of the different illustrative embodiments may be used to make measurements of spaces between parts during, for example, without limitation, component and subassembly manufacturing 106 and system integration 108.

The different illustrative embodiments recognize and take into account a number of different considerations. For example, the different illustrative embodiments recognize and take into account that a certain level of fit between parts may be desired but may not always be possible. For example, during manufacture of an aircraft wing assembly, the skin of a wing may be attached to a spar of the aircraft frame. The skin and spar may be examples of adjacent pieces that may benefit from the use of a shim. A shim may be placed in the space between adjacent parts. In certain cases, placement of the shim may be assisted by temporarily joining the parts together. The different illustrative embodiments also recognize and take into account that a clamping device may be used to temporarily join parts together. In the aviation industry, various kinds of clamps may be used. However, it may be desirable not to cause inconsistencies on the surfaces of the materials being assembled by using too large a clamping force that may result in any out of tolerance inconsistencies on the surface and/or in the structure of the materials. As used herein, an inconsistency may be an undesired change in a part. The undesired change may be on the surface, in the structure of the part, and/or some other undesired change.

However, current clamping devices may not allow for a temporary clamping with a desired level of force that avoids inconsistencies on a part. Additionally, current clamping devices may provide a variable clamping force that depends on factors such as the thickness of a work piece. Thus, the different illustrative embodiments may provide a method and apparatus for providing a clamp for use in assembling parts, such as components assembled in the manufacture of an aircraft. The clamp may be used on a temporary basis and may provide a force that has a level low enough to avoid causing inconsistencies in the parts being assembled.

An illustrative embodiment of a clamp may include a body with a channel. The body may have an interior region and exterior region and also may have a first end and a second end, with one end configured to contact a first surface of a work piece. A fastener system may be partially disposed within the channel and may be configured to move within the interior region of the body and through a hole in the work piece to a second surface of the work piece in which the fastener system may have an end configured to engage the second surface of the work piece. The clamp also may include a biasing mechanism connected to the fastener system in which the biasing mechanism may be configured to apply a force on the fastener system that may cause the second end of the fastener system and the body to engage the work piece.

With reference now to Figure 3, an illustration of a block diagram of a clamping environment is depicted in accordance with an illustrative embodiment. In this example, clamping environment 301 may include clamp 303 that may be used in conjunction with work piece 302. In an illustrative embodiment illustrated in Figure 3, clamp 303 may be implemented to temporarily clamp work piece 302.

Work piece 302 may take many different forms or embodiments. In one illustrative embodiment, work piece 302 may comprise aircraft 305 or a part or component of aircraft 305. For example, work piece 302 may comprise skin 307, plies 309, or reinforcing structure 311. Work piece 302 may include first surface 312 and second surface 313, such as an upper surface and a lower surface of work piece 302. Work piece 302 may include hole 315 which may extend through first surface 312 to second surface 313.

As used herein, work piece 302 may include one or more components. For example, work piece 302 may include multiple layers of plies 309. Work piece 302 may include skin 307 and reinforcing structure 311. Reinforcing structure 311 may take the form of a structure such as a stringer, a frame, a strut, or a spar, for example, without limitation. Other combinations of components may be assembled so as to constitute work piece 302.

Clamp 303 may include cap 320, body 330, rod 340, nut engager 350, and biasing mechanism 360. Clamp 303 may also include clutch 370. In one illustrative embodiment, clutch 370 may comprise a separate piece that may be attached to and removed from clamp 303. However, other configurations of clutch 370 may be possible, such as an attached form of clutch 370.

Body 330 may comprise a generally elongate structure. Body 330 may take the general form of a tube. In an illustrative embodiment, body 330 may be a generally cylindrical structure characterized by axial length 331, interior region 332, and exterior region 333. Body 330 may take other cross-sectional forms including, for example, without limitation, rectangular, square, and triangular. Body 330 may further include first end 334 and second end 335. Either or both of first end 334 and second end 335 may include aperture 336 providing communication between interior region 332 and exterior region 333.

Rod 340 may comprise a moveable member partially positioned in interior region 332 of body 330 and partially positioned in exterior region 333 of body 330. Rod 340 may include tangs 341. In one embodiment, rod 340 may include a pair of tangs 341. In another embodiment, rod 340 may include more than two tangs 341. Tangs 341 may comprise teeth 342 at a distal end thereof. Teeth 342 may be ridged structures at the end of tangs 341 that allow tangs 341 to engage first surface 312 or second surface 313 of work piece 302.

Tangs 341 may be configured to extend from rod 340 such that tangs 341 extend through aperture 336 into exterior region 333 of body 330. Tangs 341 may be separated by slit 344 in rod 340. Tangs 341 may include one tooth on each of tangs 341 to form teeth 342. Tangs 341 may also be formed with a tension or bias such that at rest, tangs 341 may be in radially compressed position 345, or in other words, tangs 341 when at rest may tend to retract inwardly toward each other.

In radially compressed position 345, tangs 341 may be in proximity with each other such that tangs 341 may pass through hole 315 in work piece 302. Tangs 341 may be extended to transition from radially compressed position 345 to radially extended position 346. Tang extender 343 may be positioned within slit 344. Tang extender 343 may assist in transitioning tangs 341 from radially compressed position 345 to radially extended position 346 and vice versa as tangs 341 move in and out of body 330. In radially extended position 346, tangs 341 may be extended such that teeth 342 engage first surface 312 or second surface 313 of work piece 302. The engagement of teeth 342 with work piece 302 may allow a clamping of work piece 302.

Rod 340 may include threads 349. Threads 349 may be configured to engage with cap 320. Cap 320 may include reciprocal threading 381 so as to engage threads 349 of rod 340.

Rod 340 also may comprise nut 347. Nut 347 may take the form of hex nut 348; however, other shapes, such as a square also may be possible. In one illustrative embodiment, nut 347 may be fixedly attached to rod 340. As explained further herein, hex nut 348 may be slidably held in nut receiving region 351 of body 330 such that nut 347 may slide along axial length 331 but may not be able to rotate. Because nut 347 may not be able to rotate, rod 340 may not be able to rotate.

Body 330 in its interior region 332 may further comprise nut engager 350. Nut engager

350 may take the form of nut receiving region 351 or hex nut receiving region 352. Nut receiving region 351 may be configured to receive nut 347. When nut 347 takes the form of hex nut 348, hex nut receiving region 352 may be configured with a hexagonal shape to receive hex nut 348. Nut receiving region 351 may contact nut 347 so as to substantially prevent nut 347 from rotating within interior region 332 of body 330. However, nut receiving region 351 may have length 353 so that nut 347 may be free to move along axial length 331 of body 330. Nut engager 350 also may include first stop 391 and second stop 392. First stop 391 and second stop 392 may set limits to the travel of nut 347 within nut receiving region 351. Thus, the distance between first stop 391 and second stop 392 also may set a limit to the degree of axial travel allowed to rod 340.

Other configurations in addition to nut 347 and nut engager 350 may also be used to allow axial travel of rod 340 while also preventing rotation of rod 340. For example, rod 340 may include a pin that slides within a raceway of body 330. The pin may be allowed to travel between first stop 391 and second stop 392.

Biasing mechanism 360 may be positioned within interior region 332 of body 330.

Biasing mechanism 360 may comprise spring 361, such as a coiled spring. Biasing mechanism 360 may surround rod 340. Biasing mechanism 360 may be held between rest 383 positioned on body 330 and also against seat 384 of cap 320. Additionally, a washer or plurality of washers may be used in conjunction with rest 383 and seat 384 so as to hold biasing mechanism 360 in the desired position. In this manner, biasing mechanism 360 may exert a force against rod 340 as rod 340 moves along axial length 331 of body 330.

Cap 320 may also be connected to rod 340. Cap 320 may extend through aperture 336 in second end 335 of body 330 such that cap 320 extends to exterior region 333 of body 330. Cap 320 may be connected to rod 340 through engagement with threads 349 on rod 340. Cap 320 may include flange 359 that rotatably holds cap 320 in body 330 and prevents cap 320 from disconnecting from body 330. Further, cap 320 may have a diameter and exterior surface configured to receive clutch 370.

Cap 320 and rod 340 may be threadedly connected such that a rotation of cap 320 in a desired rotational direction may move cap 320 along axial length 331 of rod 340 onto rod 340. When clamp 303 engages work piece 302, first end 334 of body 330 may contact first surface 312, and teeth 342 of tangs 341 may contact second surface 313 of work piece 302. In such a position, rod 340 may be prevented from axial movement 355 relative to body 330. Continued rotation of cap 320, which may tend to move rod 340 in that axial direction, instead may cause cap 320 to advance onto the threaded connection with rod 340. The rotation thus may cause an advancement that draws cap 320 through aperture 336 and into interior region 332 of body 330. While cap 320 is rotated and advances axially along rod 340, biasing mechanism 360 may also be compressed. Thus, continued rotation of cap 320 may cause a force from biasing mechanism 360 to develop. This force may act as a clamping force of clamp 303.

Clutch 370 may be reversibly attached to cap 320. Clutch 370 may, therefore, comprise reversible clutch 371. Clutch 370 may be attached to cap 320 in first position 372 such that clutch 370 may only rotate in one direction, such as a clockwise direction. Clutch 370 may then be removed from cap 320, reversed, and attached in second position 373. In second position 373, clutch 370 may only rotate cap 320 in a second direction, such as counterclockwise. In this manner, clutch 370 may be configured to removably attach to cap 320. A commercial example of clutch 370 that may be used with clamp 303 is offered by Monogram Aerospace Fasteners of Los Angeles, California.

The operation of clutch 370 with cap 320 and rod 340 may further be characterized by a limited amount of travel 357 permitted to cap 320. As clutch 370 rotates cap 320, cap 320 may advance along rod 340. Clutch 370, however, may be in contact with second end 335 of body 330 and may be prevented from advancing with cap 320. Continued rotation of clutch 370 may continue to rotate cap 320 and thus tend to pull cap 320 out of clutch 370. Depending on the rotation, clockwise or counterclockwise, cap 320 may tend to move into body 330 or out of body 330. As cap 320 continues to move into body 330, clutch 370 may eventually disengage from cap 320 after a sufficient length of travel 357. This length of travel 357 also may represent one limit to the compression of biasing mechanism 360. The maximum force of biasing mechanism 360 may also be limited by the total possible compression length of biasing mechanism 360. In one embodiment, without limitation, the maximum force may be about 10 pounds of force or another amount of force. In another example, with appropriate biasing mechanism 360, the maximum force may be set to about 15 pounds, about 20 pounds, about 25 pounds, about 30 pounds, or any other different higher or lower amount of force. This maximum force, which may also be referred to as the clamping force, may also be a predetermined or desired level of force.

Clutch 370 may include rollers 377 configured to engage with cap 320. Rollers 377 may be configured such that rotation of clutch 370 imparts a rotation on cap 320 through the engagement of rollers 377 with cap 320. As cap 320 moves relative to clutch 370, rollers 377 may begin to disengage from cap 320. At a distance of disengagement, rollers 377 may disengage from cap 320 such that the rotation of clutch 370 no longer rotates cap 320. Thus, the length of rollers 377 may determine the travel of cap 320 before clutch 370 disengages from cap 320, and thus the length of rollers 377 also may determine a clamping force applied by clamp 303.

As stated, clutch 370 may be attached in first position 372, reversed, and then attached in second position 373. Rollers 377 may be configured so as to rotate cap 320 in each of first position 372 and second position 373. Further, rollers 377 may be configured as ratcheting rollers such that rollers 377 only impart rotation to cap 320 in a single rotational direction in each of first position 372 and second position 373.

The effect of clutch 370 may be to determine a level of force for clamping work piece

302 regardless of the thickness of work piece 302 and regardless of how far tangs 341 extend through work piece 302. Provided that clamp 303 is properly sized for work piece 302 such that tangs 341 may pass through work piece 302 and such that teeth 342 of tangs 341 may engage with second surface 313 of work piece 302, clutch 370 may operate so as to set up a desired level of clamping force. Because clutch 370 may disengage from cap 320 after cap 320 has traveled a desired distance into body 330, that amount of travel 357 also may define the maximum force for clamp 303. The maximum amount of travel for cap 320 that is allowed by clutch 370 also may impart a maximum compression of biasing mechanism 360. The maximum force may not be dependent on either the thickness of work piece 302 or how far tangs 341 have extended so as to engage work piece 302. At different levels of extension of tangs 341 into work piece 302, clamp 303 may set up a maximum clamping force. Regardless of the thickness of work piece 302 and regardless of how far tangs 341 have extended to engage work piece 302, it may be the linear travel of cap 320 that imparts the clamping force. Further, regardless of the thickness of work piece 302 or the extension of tangs 341, cap 320 may be set to a maximum extension from body 330 by rotating cap 320 in the direction that causes cap 320 to extend from body 330. Flange 359 of cap 320 may contact body 330, stopping the extension of cap 320 at a point of maximum extension from body 330. From the point of maximum extension, cap 320 may then be rotated so as to enter into body 330 and so as to set up the clamping force. As described, it may then be the rotation of clutch 370 that determines the maximum travel of cap 320 along axial length 331 and thus the maximum clamping force.

In a further embodiment, body 330 may be configured with first closure 395 and second closure 396. First closure 395 may attach to first end 334 of body 330, and second closure 396 may attach to second end 335 of body 330. First closure 395 and second closure 396 may be attached by any means, such as, for example, threading. First closure 395 and second closure 396 may be removed so as to allow access to interior region 332 and components of clamp 303. If, for example, it is desired to change biasing mechanism 360 or rod 340, first closure 395 and second closure 396 may be removed. Thus, different kinds of forces may be allowed by using biasing mechanism 360 with a desired force.

Additionally, different lengths of rod 340 may be used depending on, for example, the thickness of work piece 302. Rod 340 having tangs 341 that are lengthy may be used with a thicker work piece 302. Rod 340 having tangs 341 that are shorter may be used with a thinner work piece 302. In this manner, multiple rods 340 of different overall lengths may be used with one body 330.

Positioner 397 may be positioned in interior region 332. Positioner 397 may take the form of a spring, such as a coiled spring, although other types of biasing devices may be possible for positioner 397. Positioner 397 may tend to press against rod 340 and to hold rod 340 against second stop 392. Positioner 397 may have a weaker force value than biasing mechanism 360.

Clamp 303 may also be configured so that an operator may manually manipulate cap 320 so as to cause a partial movement of rod 340. The movement of rod 340 may cause a movement of tangs 341. For example, when clamp 303 is not engaged in clamping work piece 302, an operator may press on cap 320. The overall design of clamp 303 may allow an operator to grasp body 330 with his hand while pressing on cap 320 with his thumb. Pressing on cap 320 also may act to push on rod 340 because of the threaded connection between cap 320 and rod 340. Cap 320 may be allowed to move as seat 384, which may be attached to cap 320, and may be allowed for movement within interior region 332. However, the movement of rod 340 and cap 320 may be resisted by positioner 397. Positioner 397 may thus be selected with a sufficiently low force such that the thumb force of an operator may overcome the force positioner 397 exerts on rod 340. In this manner, a user may adjust the extension of tangs 341 so as to bring teeth 342 into contact with second surface 313 of work piece 302 prior to the compression of biasing mechanism 360. Once contact is made between teeth 342 and second surface 313 of work piece 302, biasing mechanism 360 may be further compressed as described above with rotation of clutch 370.

The illustration of clamping environment 301 in Figure 3 is not meant to imply physical or architectural limitations to the manner in which an illustrative embodiment may be implemented. Other components in addition to and/or in place of the ones illustrated may be used. Some components may be unnecessary. Also, the blocks may be presented to illustrate some functional components. One or more of these blocks may be combined, divided, or combined and divided into different blocks when implemented in an illustrative embodiment.

In an illustrative embodiment of the disclosure, the configuration of the clamp may include a body, a rod, a cap, a biasing mechanism, and a pair of tangs. A first end of the body may be configured to engage a first surface of the work piece. The body may include an interior region, and the body may be characterized by an axial length. The rod may be positioned partially within the body. The rod may be configured to move along the axial length of the body and threading positioned on the rod. The cap may be threadedly attached to the rod such that rotating the cap may cause the cap to move axially along the body. The biasing mechanism may be connected to the rod, the body, or the cap such that axial movement of the rod beyond a desired point may engage the biasing mechanism. Rotation of the cap may be configured to compress the biasing mechanism. The biasing mechanism may be configured to establish a clamping force. The pair of tangs may be connected to the rod and may be configured to transition between an extended position and a compressed position. The tangs may be configured to engage a second surface of the work piece.

In a further illustrative embodiment of the disclosure, a clamp may include a spring positioned in an interior region of a body. A first end of the spring may rest against a rest and a second end of the spring may rest against a seat of a cap. As the cap may be rotated in a first direction, it may tend to compress the spring, and as the cap may be rotated in a second direction, it may tend to decompress the spring. Compression of the spring may transfer to a rod of the clamp as a clamping force.

In a further illustrative embodiment, a clamp may include a rod. A nut may be attached to the rod, and the nut may travel axially in a nut receiving region in an interior region of the clamp. The nut receiving region may have a first stop and a second stop which may act as limits to axial travel of the nut. The limit of travel of the nut also may set a limit of travel for the rod.

In a further illustrative embodiment, a clamp may include a positioner, such as a spring. The positioner may tend to push against a rod of the clamp so as to keep the tangs connected to the rod in a retracted position.

With reference now to Figure 4, an illustration of an aircraft on which a clamp may be used is depicted in accordance with an illustrative embodiment. In this illustrative example, a diagram of clamps 465, 466, 467, and 468 may be depicted in accordance with an illustrative embodiment. Clamps 465, 466, 467, and 468 may be shown as engaged with parts on aircraft 405. Clamps 465, 466, 467, and 468 may not necessarily be drawn to scale with respect to aircraft 405. Clamps 465, 466, 467, and 468 may be implemented using clamp 303 in Figure 3. In this example, clamps 465, 466, 467, and 468 may be examples of a physical implementation of clamp 303 shown in block form in Figure 3.

In this illustrative example, clamps 465, 466, 467, and 468 may be used in conjunction with aircraft 405. Aircraft 405 may be an example of one physical implementation of aircraft 200 in Figure 2. Aircraft 405 may include wing 406. Wing 406 may include skin 407 and struts 411. Struts 411 may be shown in dashed lines to illustrate that struts 411 may be positioned below skin 407. Skin 407 and struts 411, in this example, may illustrate one example of work piece 302 in Figure 3. The plurality of clamps 465, 466, 467, and 468 may be positioned as shown so as to temporarily clamp skin 407 to struts 411. Further, clamps 465, 466, 467, and 468 may temporarily clamp skin 407 and struts 411 with a maximum amount of force. While temporarily clamped together, other work operations may take place with respect to skin 407 and struts 411, such as, for example, shimming and boring.

Figure 4 may represent one illustrative embodiment of an application of clamp 465. A clamp, such as clamp 465, may also be used in other usages and applications. For example, clamp 465 may also be used to clamp multiple plies in a layup of composite materials. The relatively low force of clamp 465 may provide adequate clamping force for usage with composite materials so as to clamp plies together, but also desirably may avoid excessive force that may cause out of specification inconsistencies on a surface of composite materials. A clamp, such as clamp 465, may also be used to clamp a composite skin to a support structure prior to installing permanent fasteners. Many other usages and applications of a clamp, such as clamp 465, may also be achieved.

With reference now to Figure 5, an illustration of a diagram of a clamp is depicted in accordance with an illustrative embodiment. In this example, clamp 503 may be an example of a physical implementation of clamp 303 shown in block form in Figure 3. Additionally, clamp 503 may be an example of clamps 465, 466, 467, and 468 in Figure 4.

In this illustrative example, clamp 503 may be used in conjunction with work piece 502. Work piece 502 may include first ply 509 and second ply 509a. Cap 520 may be shown extending from second end 535 of body 530. Pair of tangs 541 may be shown extending below work piece 502. Tangs 541 may include a pair of teeth 542. First end 534 of body 530 may be depicted in contact with first surface 512 of work piece 502. Although not depicted in Figure 5, tangs 541 may be drawn into the interior region of body 530 so as to draw pair of teeth 542 into contact with second surface 513 of work piece 502, thereby completing the clamping of work piece 502.

Still referring to Figure 5, movement of components of clamp 503 also may be illustrated. Cap 520 may be configured to rotate in a first direction as shown in arrow 566. It is noted that cap 520 may also be rotated in the opposite direction. Described in other words, cap 520 may be configured so as to rotate both clockwise and counterclockwise.

Rotation of cap 520 also may act to move cap 520 in axial directions shown by arrow 567. It is noted that cap 520 may move in a generally upward or downward direction, relative to surface 512. Rotation of cap 520 in the direction of arrow 566 may tend to move cap 520 in one of axial directions of arrow 567, depending on the cut of threads 349 as depicted in Figure 3. Rotation of cap 520 in the opposite direction of arrow 566 may tend to move cap 520 in the opposite one of axial directions of arrow 567. The movement of cap 520 in axial directions of arrow 567 also may move cap 520 into body 530 or out of body 530. Thus, depending on the direction and amount of rotation that cap 520 receives, cap 520 may extend fully or less than fully from body 530.

Turning now to Figure 6, an illustration of a cross-sectional diagram of a clamp minus the work piece as illustrated in Figure 5 is depicted in accordance with an illustrative embodiment. Figure 6 may be an illustration of a cross-sectional diagram following cross- sectional lines 6-6 of Figure 5. In this view, clamp 603 may be depicted with tangs 641 in radially compressed position 645. Tangs 641 may be in a relaxed state, meaning that tangs 641 may be in proximity and present a narrow profile. Thus, tangs 641 may be introduced into a hole of a work piece in this configuration. It is noted that cap 620 may be rotated. Further, the rotation may take place using a clutch (not shown). Rotation of cap 620 may act to advance cap 620 along rod 640. Advancement of cap 620 relative to rod 640 may compress biasing mechanism 660 thereby providing a clamping force on tangs 641. It is noted that rod 640 and biasing mechanism 660 may be positioned within the channel or interior region 632 of body 630.

Figure 6 also may show various features of clamp 603. Features may include first end 634 and second end 635, aperture 636, and nut 647. Nut 647 may be shown traveling in nut receiving region 651. Further, nut 647 may be shown as running between first stop 691 and second stop 692. Biasing mechanism 660 may include spring 661. Spring 661 may contact rest 683 and seat 684. Seat 684, which may be attached to cap 620, may have a freedom to travel within interior region 632 along axial length 631. Rod 640 and tangs 641 may be shown as extending along axial length 631 of body 630. Tangs 641 may also be shown as including slit 644 and teeth 642. Tangs 641 may be positioned about tang extender 643. Threads 649 may be shown on rod 640. Positioner 697 may be disposed within body 630 and may be configured to press against rod 640. Positioner 697 may take the form of a spring and may be positioned around tangs 641.

Referring still to Figure 6, the physical dimensions of clamp 603 may vary. In an illustrative embodiment, body 630 of clamp 603 may comprise a generally cylindrical shape. Tangs 641 may extend out of body 630. Cap 620 also may extend out of body 630. Cap 620 may take different lengths in different embodiments. In one illustrative embodiment, cap 620 may extend out of body 630 even when tangs 641 are at maximum extension from body 630. The length of body 630 may be shown by reference number 617. For example, without limitation, length 617 of body 630 may be between about 4 inches to about 5 inches or another length. The diameter of body 630 may be indicated by reference number 619. For example, without limitation, diameter 619 of body 630 may be between about 0.625 inches to about 1.25 inches. Alternatively, diameter 619 of body 630 may be of any other size.

With respect to the clamping force exerted by clamp 603, the force also may vary but may be applied to a maximum force. For example, without limitation, in the illustrative embodiment, where clamp 603 may be used to temporarily clamp skin 407 and struts 411 in Figure 4, the clamping force may be set not to exceed about 10 pounds of force or another appropriate amount of force. As further explained herein, the maximum clamping force may be achieved by fully rotating cap 620 so as to impart the maximum axial movement of cap 620 allowed by the clutch. A lesser amount of rotation and axial movement of cap 620 may impart a lesser force.

Cap 620 may be placed in a position of maximum extension from body 630 by rotating cap 620 in the direction that causes cap 620 to extend from body 630. Cap 620 may be so moved until flange 685 attached to cap 620 contacts body 630 and is stopped from further axial movement. At the point of maximum extension, the clutch may be attached and may rotate cap 620 such that cap 620 moves back into body 630. The clutch may rotate cap 620 until the clutch disengages. The amount of axial movement imparted onto cap 620 also may cause a linear compression of spring 661. The linear compression of spring 661 may set up the clamping force. It may be a maximum clamping force because the maximum linear compression of spring 661 may be established by the maximum axial movement allowed to cap 620.

Further, the maximum clamping force may be applied regardless of the thickness of the work piece. Once teeth 642 have been brought into contact with a surface of the work piece and first end 634 of body 630 is likewise in contact with an opposing surface of the work piece, rod 640 may be restricted from any significant axial movement that may tend to compress the work piece. However, regardless of the thickness of the work piece, or in other words, regardless of how far rod 640 has been extended so as to make contact with the work piece, cap 620 may be extended to its maximum extension from body 630. From that position of maximum extension, cap 620 may be rotated so as to apply the clamping force. Thus, the constant or maximum clamping force may be applied regardless of the thickness of the work piece.

Turning now to Figure 7, an illustration of a cross-sectional diagram of a clamp as illustrated in Figure 5 is depicted in accordance with an illustrative embodiment. Figure 7, like Figure 6, may be an illustration of a cross-sectional diagram following cross-sectional lines 6-6 of Figure 5. Figure 7 may illustrate the same features as Figure 6 and thus the same reference numbers may be used in Figure 7 as were used in Figure 6. In Figure 7, clamp 603 may be depicted with tangs 641 in axially retracted and radially extended position 700. Tangs 641 may be moved, as rod 640 may move, such that tangs 641 may be pulled over tang extender 643. Tang extender 643 may be positioned in slit 644 and here may act to expand tangs 641 in the radial directions indicated by arrows 702 and 704. Thus, tangs 641 now may define a spatial relationship such that pair of tangs 641 may not be pulled through a hole in a work piece. Rather, teeth 642 may engage a surface of the work piece. As biasing mechanism 660 is further tightened, by rotating cap 620, a force may be established between teeth 642, tangs 641, and first end 634 of body 630. The force that is established may be a maximum force that may depend on the compressed length of spring 661.

Turning now to Figure 8, an illustration of a diagram of a clutch for use with a clamp is depicted in accordance with an illustrative embodiment. In this example, clutch 870 may be an example of a physical implementation of clutch 370 shown in block form in Figure 3. Clutch 870 may define cap receiving region 875. Cap receiving region 875 may be configured to engage cap 620 as shown in Figure 6. Cap receiving region 875, when engaged with cap 620, may translate a rotation of clutch 870 into a rotation of cap 620. Clutch 870 may further define grip 877 by which an operator or worker may manually grasp clutch 870. Clutch 870 may be reversible and may attach to cap 620 in either first position 872 or second position 873. First position 872 may be achieved by attaching clutch 870 with a first side placed downward onto cap 620, and second position 873 may be achieved by reversing clutch 870. Clutch 870 may include rollers 879 or other mechanisms to impart rotation onto cap 620.

As described with respect to Figure 3, clutch 870 may be configured so as to engage and then disengage from cap 620. When cap 620 is positioned so as to extend a sufficient length from second end 635 of body 630, cap 620 may be engage with cap receiving region 875 of clutch 870. The length of extension of cap 620 from body 630 may be achieved by rotating cap 620 in the direction of rotation that causes cap 620 to extend. If desired to move cap 620 to its maximum extension, cap 620 may be rotated until flange 685 contacts body 630. As clutch 870 is rotated, cap 620 may rotate and advance into interior region 632 of body 630. Cap 620 may advance a sufficient amount until it disengages from clutch 870 and clutch 870 may no longer grasp cap 620.

While clutch 870 in Figure 8 may be depicted as substantially cylindrical in shape and manually operated, clutch 870 may take other shapes and embodiments and may be operated in a different manner. For example, without limitation, clutch 870 may be adapted to receive a powered form of operation. In this manner, clutch 870 may be adapted to receive a driver, a drill, an electric motor, or another form of device that imparts powered rotation on clutch 870. Additionally, clutch 870 may be adapted to receive a wrench, a ratchet wrench, or another form of manual device that applies rotation. As for its shape, clutch 870 may take other forms, such as, for example, without limitation, angled, square, and hexagonal.

With reference now to Figure 9, an illustration of a flowchart of a process for clamping is depicted in accordance with an illustrative embodiment. The process may be generally designated by reference number 900 and may be a process for temporarily clamping a work piece including a first part and a second part. One example of the process may be temporarily clamping a work piece comprising a skin and a strut in an aircraft as depicted in Figure 5. The method may be implemented, for example, using clamp 603 in Figure 6 and Figure 7 interacting with work piece 302 of Figure 3, and the following reference numbers may track the structures and features of those figures.

Process 900 may begin by inserting pair of tangs 641 into work piece 302 (operation 901). Tangs 641 may be positioned in radially compressed position 645, that is to say their natural or relaxed position. In this position, tangs 641 may be sufficiently close together so that tangs 641 may pass through hole 315 in work piece 302.

In a further step, clutch 370 may be attached to cap 620 (operation 902). Cap 620 may extend a sufficient distance beyond second end 635 of body 630 such that clutch 370 may be engaged with cap 620. Further, clutch 370 may engage cap 620 in one of two reversible positions such that rotation of clutch 370, and thereby rotation of cap 620, may act to advance cap 620 along the length of rod 640 such that cap 620 may move into interior region 632 of body 630.

In a further step, cap 620 may be rotated (operation 903). Rotation of cap 620 may occur by the rotation of clutch 370. Rotation of cap 620 may cause cap 620 to advance along threads 649 of rod 640. Rod 640 eventually may reach a point where its axial movement is no longer possible. This may be because tangs 641 have made contact with first surface 312 of work piece 302. Also, further axial movement of rod 640 may be prevented if teeth 642 on tangs 641 contact with first end 634 of body 630. Once movement of rod 340 along axial length 631 of body 630 is prevented, the further rotation of cap 620 may cause cap 620 to advance along rod 640 and move into interior region 632 of body 630.

In a further step, tangs 641 may be expanded (operation 904). Tangs 641 may be positioned around tang extender 643. Movement of tangs 641 may draw tang extender 643 through slit 644 in tangs 641 such that pair of tangs 641 may transition from radially compressed position 645 to radially extended position 700. In radially extended position 700, tangs 641 may have become wider and may not move through hole 315 of work piece 302.

In a further step, tangs 641 may engage with first surface 312 of work piece 302 (operation 905). Rod 640 and tangs 641 may be moved until tangs 641 make contact with first surface 312 of work piece 302. The contact may include pair of teeth 642 making contact with first surface 312. In a further step, body 630 of clamp 603 may contact second surface 313 of work piece 302 (operation 906). More particularly, first end 634 of body 630 may contact second surface 313 of work piece 302. First end 634 may comprise a substantially flat surface so as to make a stable and substantial contact with second surface 313.

In a further step, cap 620 may continue to rotate until clutch 370 disengages from cap 620

(operation 907). Cap 620 may continue to move into interior region 632 of body 630 until clutch 370 may no longer engage with cap 620. At this point, cap 620 may no longer be rotated. Cap 620 may no longer compress biasing mechanism 660. The force established at this point may be the maximum clamping force for clamp 603.

Because clutch 370 may disengage from cap 620 after cap 620 has traveled a desired distance into body 630, that amount of travel also may define the maximum force for clamp 603. The maximum force may not be dependent on either the thickness of work piece 302 or how far tangs 641 may have extended so as to engage work piece 302. At different levels of extension of tangs 641 into work piece 302, clamp 603 may set up a maximum clamping force.

With reference now to Figure 10, an illustration of a flowchart of a process for unclamping a work piece is depicted in accordance with an illustrative embodiment. The process may be generally designated by reference number 1000 and may be a process for unclamping a work piece including a first part and a second part. One example of the process may be unclamping a skin and a strut in an aircraft as depicted in Figure 5 that have been subjected to clamping. The method may be implemented, for example, using clamp 603 in Figure 6 and Figure 7 interacting with work piece 302 of Figure 3, and the following reference numbers may track the structures and features of those figures.

Process 1000 may begin by attaching clutch 370 in reverse position on cap 620 (operation 1001). The reverse position may be the opposite position as compared to the manner in which clutch 370 was attached to cap 620 for clamping. For example, if clutch 370 had been attached in first position 372 for clamping, it may be attached in second position 373 for unclamping.

In a further step, clutch 370 may be rotated (operation 1002). This rotation may act to rotate cap 620, which may move cap 620 outwardly along rod 640 so as to move cap 620 into exterior region 333 of body 630.

In a further step, rod 640 may be extended (operation 1003). As cap 620 may be moved outwardly into exterior region 333, the compression set up on biasing mechanism 660 may be relaxed. Biasing mechanism 660 thus may tend to push against rod 640 so as to move tangs 641 away from contact with first surface 312 of work piece 302. Biasing mechanism 660 may act against rod 640 by pushing on rest 683 and seat 684.

In a further operation, tangs 641 may be compressed (operation 1004). As tangs 641 extend and move away from first surface 312, tangs 641 also may move away from tang extender 643. The tips of tangs 641, where pair of teeth 642 may be located, may move into their natural position, radially compressed position 645.

In a further operation, tangs 641 may be withdrawn through work piece 302 (operation 1005). Tangs 641, when in radially compressed position 645, may present a profile that is narrower than hole 315 of work piece 302. Tangs 641 may be withdrawn through hole 315. At this point, the clamping may be completed. Further work on work piece 302 or aircraft 305 may proceed as needed.

The flowcharts and block diagrams in the different depicted embodiments illustrate the architecture, functionality, and operation of some possible implementations of apparatuses and methods in an illustrative embodiment. In this regard, each block in the flowcharts or block diagrams may represent a module, segment, function, and/or a portion of an operation or step.

In some alternative implementations of an illustrative embodiment, the function or functions noted in the blocks may occur out of the order noted in the figures. For example, in some cases, two blocks shown in succession may be executed substantially concurrently, or the blocks may sometimes be performed in the reverse order, depending upon the functionality involved. Also, other blocks may be added in addition to the illustrated blocks in a flowchart or block diagram.

In an illustrative embodiment of the disclosure described herein, a method and apparatus for providing a temporary, low force clamp for use in assembling parts, such as components assembled in the manufacture of an aircraft, may be described. An illustrative embodiment of a clamp may include a body with a channel. The body may have an interior region and exterior region and also may have a first end and a second end, with one end configured to contact a first surface of a work piece. A fastener system may be partially disposed within the channel and may be configured to move within the interior region of the body and through a hole in the work piece to a second surface of the work piece. The fastener system may have an end configured to engage the second surface of the work piece. The clamp also may include a biasing mechanism connected to the fastener system in which the biasing mechanism may be configured to apply a force on the fastener system so as to cause the second end of the fastener system and the body to engage the work piece. In one illustrative embodiment, the biasing mechanism and fastener system may allow a clamping force of up to about 10 pounds force.

In an illustrative embodiment of the disclosure, the configuration of the clamp may include a body, a rod, a cap, a biasing mechanism, and a pair of tangs. A first end of the body may be configured to engage a first surface of the work piece. The body may include an interior region, and the body may be characterized by an axial length. The rod may be positioned partially within the body. The rod may be configured to move along the axial length of the body and threading positioned on the rod. The cap may be threadedly attached to the rod such that rotating the cap may cause the cap to move axially along the rod. The biasing mechanism may be connected to the rod, the body, or the cap such that axial movement of the rod beyond a desired point may engage the biasing mechanism. Rotation of the cap may be configured to compress the biasing mechanism. The biasing mechanism may be configured to establish a clamping force. The pair of tangs may be connected to the rod and may be configured to transition between an extended position and a compressed position. The tangs may be configured to engage a second surface of the work piece.

The descriptions of the different illustrative embodiments have been presented for purposes of illustration and description, and are not intended to be exhaustive or limited to the embodiments in the form disclosed. Many modifications and variations may be apparent to those of ordinary skill in the art. Further, different illustrative embodiments may provide different features as compared to other illustrative embodiments. The embodiment or embodiments selected are chosen and described in order to best explain the principles of the embodiments, the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.

Claims

CLAIMS: What is claimed is:

1. A clamp (303) comprising:

a body (330) having an interior region (332) and having a first end (334) configured to contact a first surface (312) of a work piece (302);

a fastener system configured to move within the interior region (332) of the body (330) and through a hole (315) in the work piece (302) to a second surface (313) of the work piece (302) in which the fastener system has a second end (335) configured to engage the second surface (313) of the work piece (302); and

a biasing mechanism (360) connected to the fastener system in which the biasing mechanism (360) is configured to apply a force on the fastener system to cause the second end (335) of the fastener system and the body (330) to engage the work piece (302) at a desired level of force at different levels of extension of the fastener system.

2. The clamp (303) of claim 1, wherein the fastener system comprises a rod (340) configured to move axially relative to the body (330), the rod (340) having threads (349); and a cap (320) threadedly attached to the rod (340) such that rotating the cap (320) causes the rod (340) to move along an axial length (331) of the rod (340).

3. The clamp (303) of claim 1, wherein the biasing mechanism (360) comprises a spring (361).

4. The clamp (303) of claim 2 further comprising a clutch (370) configured to attach to the cap (320) and configured to set the desired level of force for the fastener system.

5. The clamp (303) of claim 4, wherein the clutch (370) is a reversible clutch (371).

6. The clamp (303) of claim 4, wherein the clutch (370) is configured to disengage from the cap (320) after the cap (320) advances a desired distance along the rod (340).

7. The clamp (303) of claim 2 further comprising a nut (347) and a nut engager

(350) configured to prevent rotation of the rod (340) and to allow axial motion of the rod (340).

8. The clamp (303) of claim 7, wherein the nut (347) comprises a hex nut (348) and the nut engager (350) comprises a hex nut receiving region (352).

9. The clamp (303) of claim 8, wherein the nut (347) and the hex nut receiving region (352) are configured such that the nut (347) may move axially within the nut engager

(350).

10. The clamp (303) of claim 1 further comprising a pair of tangs (341) and a tang extender (343) attached to the body (330), the pair of tangs (341) being biased to a compressed position (345), and the tang extender (343) configured to move the pair of tangs (341) to an extended position (346).

11. The clamp (303) of claim 10, wherein the pair of tangs (341) comprises teeth

(342) configured to engage a surface of the work piece (302).

12. The clamp (303) of claim 2 further comprising a positioner (397) configured to bias the rod (340) against a stop (392) of the body (330).

13. An apparatus for clamping a work piece (302) at a maximum force, the apparatus comprising:

a body (330), a first end (334) of the body (330) configured to engage a first surface (312) of the work piece (302), the body (330) having an interior region (332), the body (330) also having an axial length (331);

a rod (340) positioned partially within the body (330), the rod (340) configured to move along the axial length (331) of the body (330) and threading positioned on the rod (340);

a cap (320) attached to the rod (340) such that rotating the cap (320) causes the cap (320) to move axially along the rod (340);

a biasing mechanism (360) connected to the rod (340), the body (330), and the cap (320) configured such that axial movement of the rod (340) beyond a desired point engages the biasing mechanism (360), and rotation of the cap (320) configured to compress the biasing mechanism (360), the biasing mechanism (360) configured to establish a clamping force; and

a pair of tangs (341) connected to the rod (340), the tangs (341) configured to transition between an extended position (346) and a compressed position (345), wherein the tangs (341) are configured to engage a second surface (313) of the work piece (302).

14. The apparatus of claim 13 further comprising a clutch (370) configured to attach to the cap (320).

15. The apparatus of claim 14, wherein the clutch (370) is a reversible clutch (371) such that attaching the clutch (370) in a first configuration rotates the cap (320) in a first direction and attaching the clutch (370) in a second configuration rotates the cap (320) in a second direction.

16. The apparatus of claim 14, wherein the tangs (341) comprise a pair of teeth (342).

17. A method for clamping a work piece (302) at a desired force, the method comprising:

inserting a pair of tangs (341) through a hole (315) of the work piece (302);

rotating a cap (320) connected to a rod (340) in a first direction such that the tangs (341) engage a surface of the work piece (302); and

compressing a biasing mechanism (360) to establish a clamping force.

18. The method of claim 17, wherein the step of rotating the cap (320) further comprises attaching a clutch (370) to the cap (320) and rotating the clutch (370).

19. The method of claim 18, wherein rotating the clutch (370) extends the rod (340) to a distance and the clutch (370) then disengages the cap (320).

20. The method of claim 18 further comprising rotating the cap (320) in a second direction so as to extend the cap (320); and disengaging the tangs (341) from the work piece (302).