BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an air assisted device for positioning a workpiece, shown mounted on an assembly line trolley.
FIG. 2 is an enlarged, perspective view of the device shown in FIG. 1.
FIGS. 3 and 4 are perspective views of CAD representations of the device shown in FIG. 1.
FIG. 5 is a perspective view of a CAD representation showing the arrangement of the magnet array relative to the surface of the ball.
FIG. 6 is a cross sectional view of the device shown in FIG. 1, including an air flow control system for locking and releasing the positioning device.
FIG. 7 is a fragmentary, bottom view of the socket body, showing air channels for controlling air flow.
FIG. 8 is a cross sectional view of an alternate form of the socket body.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring first to FIG. 1, the present invention relates to an air assisted positioning device generally indicated by the numeral 10, for positioning or orienting a workpiece such as an aircraft fuselage panel 14, in any of a multiplicity of ergonomic positions to allow an assembly operator or mechanic to work on the panel 14. Broadly, the device 10 comprises a socket body 24 mounted on a ball 22 which is fixed to a support 28. In the illustrated example, the support 28 comprises the output shaft of a pneumatically operated cylinder and slide assembly 20 which controls the elevation of the panel 14. The slide assembly 20 is mounted on a wheeled trolley 16 guided along a track 18 which carries the panel 14 down an assembly line. The panel 14 is supported on a mounting fixture 12, which in turn is fixed to the socket body 24. The socket body 24, and thus the panel 14, is rotatable 180 degrees, or more around the entire surface of the ball 22, and is limited in rotational movement only by the support 28.
Referring now also to FIGS. 2-7, the ball 22 is spherical in shape and is formed of a metallic material having a large, positive magnetic susceptibility. Other suitable materials include, for example, iron, cobalt, nickel and alloys of these materials. These materials are sometimes referred to as being ferromagnetic.
The socket body 24 includes a lower body portion containing an array of permanent magnets 26 arranged such that adjacent ones of the magnets 26 have alternating north and south poles. The socket body 24 includes an upper portion defining a mounting plate 30 on which a workpiece, or workpiece holding fixture can be mounted. The socket body 24 comprises non-ferromagnetic material such as ABS, carbon fiber, nylon or other synthetic material, formed by molding or machining. In the example shown in FIG. 6, the socket body 24 is integrally molded around the magnets 26, and the mounting plate 30 is formed as a separate part which is secured to the molded socket body 24. The outer ends of the socket body 24 surrounding the magnets 24 can be seen in FIG. 6 to engage or nearly engage the ball 22, so as to create an almost air-tight socket cavity. Alternatively, however, as shown in FIG. 8, the socket body 40 can be manufactured as a single part using rapid prototyping techniques such as SLS or FDM. The one-piece, socket body 40 shown in FIG. 8 has integrally formed cavities 42 into which the magnets 26 may be inserted and fixed in place.
The permanent magnets 26 are held by the socket body 24 in an spherical array forming a partial socket. One end of each of the magnets 26 contacts the spherical surface of ball 22. Although not shown in the drawings, the outer ends or faces of the magnets 26 that contact the ball 22 may be concave shaped so as to better conform to the spherical surface of the ball 22.
As best seen in FIG. 5, the magnets 26 are arranged in an array such that their relative positions maximize the magnetic flux which attracts the ball 22. Although permanent magnets 26 are shown in the illustrated embodiment, it should be noted that electromagnets could alternately be used, although electromagnets would require wiring connections to a source of electrical power, in contrast to the simple construction provided by use of permanent magnets 26.
The semi-spherical, socket-like arrangement of the permanent magnets 26 produce a sufficient attractive force between the socket body 24 and the ball 22 to securely hold the panel 14 or other workpiece in the desired position. The socket body 24 may be rotated about the surface of the ball 22, limited only by contact with the support 28. Thus, depending upon the exact geometry and size of the socket body 24, the workpiece can be rotated 180 degrees or more.
In accordance with the present invention, the magnetic ball and socket positioner described above is assisted by the selective introduction of a flow of air between the interface of the ball 22 and the ends of the magnets 26 which contact the ball 22. As best seen in FIG. 6, an air nozzle 32 in the socket body 24 is connected with a pneumatic line 34 to a source of compressed air 36, or alternatively a vacuum. Compressed air supplied from the source 36 through the nozzle 32 is introduced at one or more openings 38 in the interior, concave shaped surface of the socket body 24, facing the ball 22. The introduction of this flow of compressed air moves the magnets 26 slightly away from the ball 22, thereby reducing the contact friction in an amount that allows the socket body 24, and thus the workpiece, to be more easily rotated to a desired position of orientation. When the workpiece has been so rotated, the compressed air supply is turned off, thus restoring the full level of friction generated by the magnets 26, locking the workpiece in place.
In those applications where the workpiece may be particularly heavy, the vacuum source 36 may be used to withdraw air from the interface between the ball 22 and magnets 26, creating a partial vacuum within the concave socket body cavity which draws the magnets 26 more tightly into engagement with the ball 22. The resulting, increased friction causes the ball and socket to resist rotation more strongly. As shown in FIG. 7, the concave inner surface of the socket body 24 surrounding the ends of the magnets 26 may be provided with grooves or channels 38 which aid in the distribution of air flow so that the compressed air (or vacuum) is applied more evenly over the entire socket area.
Although this invention has been described with respect to certain exemplary embodiments, it is to be understood that the specific embodiments are for purposes of illustration and not limitation, as other variations will occur to those of ordinary skill in the art.
Patent Application
20080054541
