Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-09-09
2001-05-08
Sells, James (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S583100, C100S321000
Reexamination Certificate
active
06228200
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to presses for forming belt joints, and more particularly to a press typically used for joining belt ends to form a belt joint.
BACKGROUND OF THE INVENTION
Belts, and more particularly conveyor belts, are typically manufactured in long strips which are spliced together in one or more locations to form a continuous loop. Due to the stresses imposed on the conveyor belts, it is important that the splice be as high a quality as possible so as to prevent, or at least delay, belt failure at the splice. Over time, a number of methods have been employed to splice belt ends together. The simplest method is the butt splice where the opposing ends of the belt are cut and then bonded together, such as by glue or stapling. Such butt splices are weak. Stronger splices are achieved when there is some sort of overlapping of the two belt ends, such as when the top half of one end and the bottom half of the other end are removed and the complementary portions of the ends are overlapped and bonded together by gluing, etc., and thereafter vulcanized with presses having heated platens. For some applications, it is desirable to form stepped splices having staggered overlapping levels, as disclosed in co-pending application Ser. No. 09/105,682, entitled “Belt Splitting Machine,” which is incorporated by reference herein in its entirety. In addition, the belt material of the complementary opposing ends may be formed into an interleaved finger arrangement.
A number of belt presses have been designed. Typically, such presses rely on either hydraulic pressure or inflatable bladders to supply the compression force between opposing platens. For instance, U.S. Pat. No. 4,946,541 to Thies et al. discloses a hydraulic press while U.S. Pat. No. 5,562,796 to Ertel discloses a inflatable bladder press. Hydraulic presses suffer from the disadvantages of requiring extra equipment, such as hydraulic pressure sources, and being unduly complicated. Inflatable bladder presses likewise require additional equipment, such as high pressure air supplies, involve undue complexity, and suffer from the potential for bladder failure.
In light of the above, there remains a need for a simplified belt press which can provide reliable performance for forming belt joints. It is preferred that such a press require a minimum of supply connections.
SUMMARY OF THE INVENTION
The belt press of the present invention generates a compression force for joining or repairing a belt between press surfaces by relying on differential thermal expansion between parts of at least one platen assembly to generate the required pressure. The belt press advantageously leverages off the high temperatures already required for good belt joint forming, rather than relying on some additional force supplier such as high pressure air or hydraulic lines.
In one preferred embodiment, the belt press includes two platen assemblies, for illustrative purposes, a top and bottom platen assembly, disposed about a section of belt. Preferably, the two platen assemblies are substantially identical, but this is not required. The platen assemblies are connected such that relative separation movement between the platen assemblies (e.g., vertically apart) is limited, typically by a plurality of clamps attached to either end of the platen assemblies. At least one of the platen assemblies has at least one, and preferably a plurality of expansion limiting rods aligned generally parallel to the platen's longitudinal axis and attached to the respective platen at or near the ends of the platen. The expansion limiting rods preferably are attached via adjustable couplings to sturdy anchor bars laterally disposed across the platen and rest against two or more bridging rods midway along the length of the platen.
The expansion limiting rods have a coefficient of thermal expansion that is smaller than the coefficient of thermal expansion for the platen, at least along the direction of the longitudinal axis. When the platen assembly is heated, the expansion limiting rods resist the thermal expansion of the platen assembly which causes the platens to bow slightly. Because the preferred bridging rods are bowed outwardly and press inwardly against the bridging rods when resisting the thermal expansion of the platen, the platens are urged to press inwardly together, thereby generating the compressive pressing force.
Preferably, the platen assemblies include an outer U-channel with a plurality of inner U-channels affixed thereto, for structural rigidity among other reasons. In addition, the platen assemblies may include several means for distributing and equalizing heat and pressure, the details of which are described below. However, other than through deflection caused by constrained thermal expansion, the platen assemblies preferably include no moving parts (other than valves, switches, and the like).
The belt press of the embodiment described immediately above includes a minimum of moving parts, thereby increasing product reliability. Most notably, the failure-prone inflatable bladders of the prior art are eliminated. The main parts of the belt press need only be supplied with electrical power and coolant to function optimally. There is no need for high pressure air or hydraulic pressure generators. In addition, because the bulk of the platen assemblies may be made from aluminum, or other light, but strong materials, the weight of the platen assemblies is reduced.
REFERENCES:
patent: 4164440 (1979-08-01), Previati
patent: 4431474 (1984-02-01), Gronek et al.
patent: 4769106 (1988-09-01), Busching
patent: 4855011 (1989-08-01), Legge et al.
patent: 4917741 (1990-04-01), Thies et al.
patent: 4946541 (1990-08-01), Thies et al.
patent: 4964943 (1990-10-01), Kruger et al.
patent: 5468315 (1995-11-01), Okada et al.
patent: 5470428 (1995-11-01), Sanko
patent: 5555798 (1996-09-01), Miyashita et al.
patent: 5562796 (1996-10-01), Ertel
patent: 5578159 (1996-11-01), Miyashita et al.
patent: 5635014 (1997-06-01), Taylor
Willis Adrian J.
Willis John A.
Belt Equipment, Inc.
Coats & Bennett PLLC
Sells James
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