Conveyors – chutes – skids – guides – and ways – Rollerways – Submerging and rising
Reexamination Certificate
1998-07-30
2001-06-12
Ellis, Christopher P. (Department: 3651)
Conveyors, chutes, skids, guides, and ways
Rollerways
Submerging and rising
C193S0350SS
Reexamination Certificate
active
06244417
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to material handling and conveyance systems, and more particularly, to a material handling unit that is part of a cargo conveyor system for loading aircraft and ocean going vessels or the like, and which uses a plurality of multidirectional helical roller assemblies.
BACKGROUND OF THE INVENTION
Cargo handling systems, such as material handling units, are used at airports and other similar locations for transferring pallets and cargo containers a relatively long distance between two locations. Some of these cargo handling systems include a steerable, self-propelled transporter, which is connected to a dolly supported on rollers. An example includes the mobile cargo handling system and method disclosed in U.S. Pat. No. 4,348,150 assigned to FMC Corporation, the disclosure which is hereby incorporated by reference in its entirety.
In these type of units, pallets or cargo containers can be conveyed along a conveyor system having driven balls that are protectable against overloading, such as a conveyor system as disclosed in U.S. Pat. No. 5,261,526, assigned to FMC Corporation, the disclosure of which is hereby incorporated by reference in its entirety. The point of contact between the driving roller and the ball is located at some distance below the horizontal plane through the center of the ball, which distance is smaller than the radius of the ball, and allows aluminum pallets and cargo containers to be transported in a direction toward a cargo hold or other area.
However, depending on the physical location and type of cargo hold or receiving area for the pallets and cargo containers, some conveyor systems do not provide a powered drive the entire distance, and thus, “dead zones” are created. The pallets or cargo containers must pass across ball mats or some other type of rolling element.
Typically in a ball mat, a large number of spherical balls have a small portion of their surface exposed to form a small point of contact for the load. These balls are typically about 30 or 40 millimeters in diameter (about 1.18 to 1.57), which sit inside the deck or platform in the “dead zone.” The balls are typically spaced about six inches apart, in accordance with International Air Transport Association (I.A.T.A.) specifications for loading equipment of palletized containers. However, these ball mats have several drawbacks. For example, the continual passing of the pallets and cargo containers across the small point contact of the ball surface damages the bottom of the aluminum pallets and cargo containers. Additionally, contaminants often are pulled into the ball mats causing corrosion. If a ball cannot rotate properly, then it is difficult to spin or shift a pallet or cargo container from side-to-side or roll the pallet or cargo container at an angle. It would then be difficult to match the angle with the applied force. As a result, this could increase operator injuries and cause damage to goods, thus raising operating costs.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a material handling unit having a roller mechanism that not only allows turning of pallets and cargo containers in the direction of applied force, but also provides a larger surface contact on the load and minimizes the chance of damage to pallets and cargo containers.
The present invention is advantageous because it now allows pallets and cargo containers to be transported on a substantially planar platform that forms a “dead zone” on a conveyor system, such as used for loading cargo holds in airplanes, ships or other cargo handling facilities. The load is spread across the surface of a roller in a multidirectional helical roller assembly. In a preferred aspect, the roller is a helical roller having an outer concave surface, forming a barrel shape, such as the type disclosed in U.S. Design Pat. No. 294,074 and U.S. Pat. Nos. 4,907,692 and 5,064,045, all assigned to FMC Corporation, the disclosures which are hereby incorporated by reference in their entirety.
The use of the helical roller having the concave outer surface in the multidirectional helical roller assembly in accordance with the present invention operates as a caster to allow the roller to turn in the direction of applied force as pallets and cargo containers are fed along a platform. The multidirectional helical roller assembly of the present invention also is maintenance free, self-draining or self-cleaning and is not prone to contamination because of the nature of inner and outer races and the large opening within the multidirectional helical roller assembly. The multidirectional helical roller assembly has a low profile so that it cannot be upended as easily. This low profile also reduces the damage from side impact of containers because of the concave or “helical” nature of the roller. The roller is also offset from the centerline of the central opening and the offset is only about one-sixth the diameter of the roller. The small offset is further achieved by the nature of the inner and outer races on inner and outer ring members such that free rotation of the inner ring member is provided.
In accordance with the present invention, a material handling unit includes a substantially planar platform having a longitudinal direction on which pallets and cargo containers are transported. A plurality of multidirectional helical roller assemblies are positioned transverse and longitudinally along the planar platform. Each of the multidirectional helical roller assemblies includes an outer ring member having an inner bearing race and an inner ring member freely rotatable relative to the outer ring member and having an outer bearing race cooperating with the inner bearing race on the outer ring member. The inner ring member forms a central opening. A roller is rotatably mounted on the inner ring member and extends transverse across the central opening and offset to a centerline defined by the central opening. The inner ring member supports the roller and is free to turn in a direction of applied force as pallets and cargo containers are transported on the platform deck.
In accordance with the preferred aspect of the invention, the substantially planar platform includes a plurality of openings. A multidirectional helical roller assembly is received within each opening. The outer ring member further comprises a horizontal flange that is positioned prone against the platform to prevent the multidirectional helical roller assembly from passing through the hole in which it is received. The helical roller has an outer concave surface and defines a barrel shaped roller having a surface point of contact that extends past a horizontal plane defined by the top surface of the outer ring member. The concave surface further defines a radius of curvature that is about 6.5 times the radius of the roller at its greatest diameter to enhance transport of cargo containers and pallets across the rolls at an angle to the longitudinal axis of the rolls.
In still another aspect of the present invention, the offset from the centerline of the central opening to the support shaft is about one-third the diameter of the roller. The diameter of the outer ring is about three to four times the diameter of the roller. A plurality of ball bearings are mounted between the inner and outer races. In one aspect of the present invention, the outer ring member further comprises a V-groove forming the inner bearing race and the inner ring member further comprises a V-groove forming the outer bearing race. The inner ring member can comprise upper and lower ring plates. The ball bearings can be inserted when the lower ring plate is removed. A shaft can be fixably mounted on the inner ring plate and rotatably support the roller. The shaft can be secured when the upper ring plate is secured against the lower ring plate.
REFERENCES:
patent: D. 294074 (1988-02-01), Sogge
patent: 3345675 (1967-10-01), Haydock
patent: 3727245 (1973-04-01), Gerth
patent: 3858271 (1975-01-01), Howard et al.
patent: 4348150 (1982-09-01), Inghra
Gou Juan F.
McKinnon Laura L.
Timmer Michael L.
Deuble Mark A.
Ellis Christopher P.
FMC Corporation
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