Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – Shaping against forming surface
Reexamination Certificate
1998-11-23
2001-01-23
Vargot, Mathieu D. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
Shaping against forming surface
C264S334000, C425S034200, C425S384000, C425S395000, C156S137000, C156S140000, C156S141000
Reexamination Certificate
active
06177042
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the molding of vehicle supporting elements formed of rubber and more particularly, to a system for molding rubber tractor tracks in an endless configuration.
2. Description of the Prior Art
Molded rubber tractor tracks are in many cases being substituted for conventional metal tractor tracks. Rubber tractor tracks offer better maneuverability, better ride quality in rough fields, better flotation in wet fields, improved side hill stability, excellent traction, low maintenance and versatility compared to steel tractor tracks. Additionally, rubber tracks are replacing conventional rubber tires on tractor and other agricultural vehicles such as combines, trenchers, snow removers, spreaders, sprayers, wagons and carts, since rubber tracks are more friendly to agricultural fields, offer better flotation and less compaction than rubber tires, resulting in better crop yield. The use of rubber tractor tracks permits farmers to get out into the fields earlier in the planting season and plant more crops as compared to rubber tire-equipped agricultural vehicles.
Rubber tractor tracks are defined by an endless rubber belt reinforced with continuous flexible steel cables bonded into the rubber. Presently, a complete rubber tractor track is molded flat in quarter sections which are sequentially then bonded together during the curing process. In practice, the joint between the bonded-together sections tend to break in use. Additionally, the joint between the bonded-together ends is of a different cross-sectional dimension than the cross-sectional dimension of the major portion of the track length. Accordingly, during movement of the track-supported vehicle, the vehicle is subject to severe vibrations. Such vibrations are not only harmful to the vehicle, but also to pavement over which the vehicle is moved. Additionally, such vibration is annoying to the vehicle operator.
Another method involves building a complete track using a drum. Uncured or cured lugs are first manually clamped within pockets formed in drum. Next, uncured rubber, calendered cord and wire cable are wrapped around the outside of the drum. Preformed uncured treads are then stitched onto the uncured rubber. The drum is then disposed within an autoclave to cure the rubber and the parts attached thereto. The drum is then collapsed to remove the completed track. Since only low pressure can be applied the cured rubber is of a low density with resulting low strength. Also, the track lugs and treads are not generally integrally bonded to the rubber and are displaced during use.
SUMMARY OF THE INVENTION
The method and apparatus for molding rubber tractor tracks of the present invention effects complete molding of an entire rubber track in an endless configuration of uniform thickness so as to eliminate any discontinuity in cross-section along the length of the rubber track. As a result, a rubber track embodying the present invention eliminates the vibration created by the bonded-together sections of a conventional rubber tractor track during vehicle movement. Additionally, a rubber tractor track embodying the present invention is not subject to breakage as in the case of a conventional rubber tractor track formed of bonded-together sections. Moreover, a rubber tractor track made in accordance with the present invention is completely integral with respect to the lugs and treads whereby the lugs and treads will not become separated from the track.
Another advantage of the method of molding rubber tire tracks embodying the present invention is the reduction in manufacturing time and cost afforded by such method, as compared to the prior art methods described above.
This advantage is broadly achieved by molding an initially uncured belt, securing drive lugs to the inner periphery of the uncured belt, inserting the uncured belt into a molding press, heating the molding press to mold treads on the outer portion of the belt while bonding the drive lugs to the inner portion of the belt, and then removing the cured belt and its drive lugs from the molding press.
The apparatus of the present invention includes a molding press having a plurality of horizontally movable outer molding segments formed with tread-defining recesses on their inner portions, a segment loader having a plurality of horizontally movable inner molding segments, each molding segment having a drive lug cavity that initially removably holds a drive lug, a belt handler for positioning an uncured belt within the confines of the inner molding segments of the segment loader, a power-operated segment loader to urge the inner molding segments outwardly to secure the drive lugs against the inner periphery of the uncured belts and a segment handler for moving the inner molding segments and uncured belt into the space encompassed by the outer molding segments of the molding press to effect curing of the belt between the inner and outer molding segments while forming the treads on the outer surface of the belt and bonding the drive lugs onto the inner portion of the belt, with the segment handler thereafter withdrawing the inner molding segments and cured belt from the molding press.
These and other features and advantages of the present invention will become apparent from the following detailed description of a preferred embodiment which, taken in conjunction with the accompanying drawings, illustrates by way of example the principles of the invention.
REFERENCES:
patent: 1579922 (1926-04-01), Gammeter
patent: 1665870 (1928-04-01), Wetmore
patent: 1715973 (1929-06-01), Abbott
patent: 1763589 (1930-06-01), Kirk
patent: 1779376 (1930-10-01), Swern
patent: 1779377 (1930-10-01), Swern
patent: 1949443 (1934-03-01), Abbott
patent: 1986092 (1935-01-01), Abbott
patent: 2747225 (1956-05-01), Zona
patent: 3222716 (1965-12-01), Harris
patent: 3791897 (1974-02-01), Mesly
patent: 3934968 (1976-01-01), Cicognani
patent: 4003686 (1977-01-01), McLeod et al.
patent: 4038001 (1977-07-01), Stinnes
patent: 4184822 (1980-01-01), Schwabauer
patent: 4510113 (1985-04-01), Takano et al.
patent: 4575438 (1986-03-01), Fike
patent: 4589941 (1986-05-01), Tanaka et al.
patent: 5104600 (1992-04-01), Remond
patent: 5204036 (1993-04-01), MacMillan
patent: 5207849 (1993-05-01), Siegenthaler
patent: 5271727 (1993-12-01), Irie
patent: 5346663 (1994-09-01), Siegenthaler
patent: 5460771 (1995-10-01), Mitchell et al.
patent: 5536464 (1996-07-01), Muramatsu
patent: 0 419 424 A2 (1990-08-01), None
patent: 2 053 786 (1979-07-01), None
patent: WO 91/04145 (1991-04-01), None
Fulwider Patton Lee & Utecht LLP
The Goodyear Tire & Rubber Company
Vargot Mathieu D.
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