Joints and connections – Structurally installed in diverse art device
Reexamination Certificate
1999-09-13
2002-02-12
Kim, Harry C. (Department: 3629)
Joints and connections
Structurally installed in diverse art device
C403S306000, C198S844200, C024S03100H
Reexamination Certificate
active
06345925
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a bolt for a conveyor belt fastener used in belt splices and, more particularly, to a conveyor belt fastener bolt that allows splices to be applied more easily and quickly and with improved strength.
BACKGROUND OF THE INVENTION
Most belt fasteners used for making belt splices have an upper member or plate and a lower member or plate that are clamped on opposite surfaces at a belt end portion that is to be spliced to another belt portion. Solid plate fasteners utilize a single plate on the upper surface and a single plate on the bottom surface spanning both end portions of the conveyor belt, whereas hinge fasteners have arcuate hinge loops that connect the upper and lower plates and which mate with loops of fasteners attached to the other belt end portion for receiving a hinge pin therethrough to provide a hinged splice. The present invention is directed to a bolt that is used with belt fasteners of either type of the above-described fasteners, i.e. solid plate or hinge fasteners.
Present conveyor belts can have a wide variety of constructions designed according to the rigors of the applications which they must withstand. The mechanical fastener chosen for a conveyor system requires taking into account the tensile strength of the belts employed and the pulley diameters in the conveyor drive system from which the belts are to be run. Conveyor belt materials are typically of a rubber or PVC construction and with various strengthening compounds, include woven materials and/or have plies of different materials running therethrough to improve the belt tensile strength. The covers of conveyor belts particularly in heavy-duty applications will have a tough, rugged construction to provide the necessary durability for the abrasive and heavy materials usually transported thereby.
With the mechanical solid plate or hinged fasteners that use bolts for clamping the plates onto the opposite surfaces of the belt end portions, one of the major considerations is the installation time and the ability of the applied fasteners to provide a good, strong splice. In both the bolt hinged and solid plate fastener systems, a template is used for forming through holes in the belt end portions for receiving the bolts of the fasteners therethrough. The punch or bores are driven as by a power tool through openings in the template into the belt carcass for accurately forming the through holes for proper fastener alignment. Inserting the threaded shanks of the bolts into and through the holes in the belt end portions can be a very difficult and time consuming task. Where the holes in the belt are tightly formed so that there is little loose play between the shank and the belt carcass material about the hole, the shank threads tend to get hung up on the belt carcass as the worker attempts to push the bolts through the holes in the belt. Because these belts are typically of very tough and rugged construction as previously described, this pushing of the bolts through the holes can take a significant amount of time and effort. With the bolt solid plate fasteners, after all bolts are inserted through the first belt end portion there remains the task of placing the holes of the other belt end portion onto the bolts of the fasteners already in place on the first belt end portion. For this purpose, the template has a comb-like edge with notches for receiving the bolts to be inserted in the belt end to help keep them aligned during this process; however, the bolts are still not totally confined and do tend to move around particularly as the worker encounters difficulty as they push the belt down onto the bolts for being inserted through the holes.
After repeated usage, the edges about the guide holes in the templates can become deformed because of engagement with the driven punch distorting the holes from their desired circular shape. Deformed template holes usually lead to inconsistent, ragged through holes formed in the belt end such as with an oval cross-sectional shape. While this provides for easier installation of the bolts through the larger ovalized through holes, there is also a greater amount of belt carcass material removed and more play between the hole walls in the belt end and the shank of the bolt therein. The larger holes and looseness of the fit between the bolts and holes in the belt end produces a weaker splice over one where the shanks of the belts are snugly received in tightly formed holes with a circular cross-sectional shape.
With the distal ends of the bolts projecting through the holes, nuts are next placed on the projecting ends of the shanks and held thereon by starting the threading of the internal threads on the nut with the threads on the shank. This presents a significant limitation in the use of current bolt fasteners, since it is often very difficult for a worker to start the threading by hand as they are often performing splicing operations in extreme conditions such as where there is poor lighting and/or in extreme cold temperatures. In the latter case, the worker is often wearing gloves making it very difficult to have the necessary tactile coordination to start the thread properly. With current bolts, there is only a very small conical lead-in tip portion at the end of the bolt onto which the nut is placed. In this position, the nut can shift around so that it is at an angle to the axis of the bolt shank, and starting the threading in this angled orientation tends to produce cross-threading between the nut and shank. A nut that is cross-threaded makes it very difficult for the wrenching operation to properly seat the nut in the aperture of the upper plate as is desired for providing the fastener with its maximum holding power and the resultant strong splice. In addition, backing the nut off the shank to avoid screwing down the nut in its cross-threaded orientation on the bolt shank is also difficult and increases installation time.
Even where the nuts have been threaded properly to the shank, when a power wrench is employed to screw the nuts down for clamping the fastener plates against the belt end portion, vibrations associated with use of the power tool can cause the nuts to loosen and fall off the ends of the shanks requiring the nuts to be picked up and placed back thereon or having the worker retrieve additional nuts for placing on the shank end. Oftentimes, splicing is occurring at an elevated location and if the nuts fall to the ground below, the worker may not have a sufficient number of nuts at the elevated location for completing the splice without having to travel down to the ground level for obtaining additional nuts generating additional delays during the installation process.
It has also been found that during shipping and handling the endmost threads on the bolt shank can be damaged adding to the difficulty in threading nuts thereto. In addition, during the installation procedure, the plates may be pounded as with an impact tool to sink teeth thereof into the belt carcass. If the impact tool inadvertently contacts the projecting shank end, the threads most likely to be damaged are those at the end thereof creating the adverse consequences for starting the threading of the nut described above.
SUMMARY OF THE INVENTION
In accordance with the present invention, a fastener is provided for splicing end portions of conveyor belts together with the fastener having a bolt with a pilot or lead-in portion that provides improved threading of a nut thereto and makes installation of the fasteners on the belt ends faster and easier. The pilot of the bolt is longer than the beveled conical tip portion of prior belts so that nuts received thereon will stay substantially aligned with the axis of the shank. In this manner, threading of the nut to the bolt shank is easier in terms of avoiding cross-threading problems. Also, as the pilot portion of the shank is free of any threads, the installation of the bolt onto the belt ends can be done more quickly with less resistance during the insertion process. With the threading of the nuts st
Fitch Even Tabin & Flannery
Flexible Steel Lacing Company
Kim Harry C.
LandOfFree
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