Tamper-evident fastening device

Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Headed fastener element with nut – washer – securing means or cap – Cap over the head

Reexamination Certificate

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Details

C411S377000, C411S909000, C411S910000

Reexamination Certificate

active

06312203

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates broadly to tamper-evident fastening devices. More particularly the invention relates to a threaded fastener such as a screw or drain plug with a tamper-evident sheath formed from a thermoshrinkable sleeve.
2. Background of Invention
Many mechanical devices contain screw-type plugs in critical functions. One such example is the oil drain plug of motors. Lube and oil change businesses incur considerable expense every year replacing or repairing motors in vehicles where a loose oil plug has led to loss of oil and failure of the motor. The loose state of the oil plug may be the result of deliberate tampering or improper maintenance by service personnel.
Given the importance of the function of these types of fasteners, it is highly desirable to have a convenient device and/or method for detecting removal or tampering. Additionally, it is desirable to have an efficient means to monitor servicing of these devices that would verify proper maintenance and installation for the purpose of quality control.
Currently, a method in common use is spraying across the device with spray paint. This method suffers the disadvantages of being easy to circumvent by one intent on deceit. This method also results in disfiguration of the equipment with splotches of spray paint and can cause confusion after multiple servicing events in which multiple layers of paint have been applied.
Thus, there is a need for a tamper-evident fastening device that can be used as a motor oil drain plug to monitor proper installation and unauthorized manipulation of such plugs.
SUMMARY OF INVENTION
It is therefore an objective of the present invention to provide a simple, economical tamper-evident fastener.
It is another objective of the present invention to provide a tamper-evident fastener that is usable as a drain plug.
It is a further objective of the present invention to provide a method of use for a tamper-evident fastener.
Toward these ends, a tamper-evident fastener for insertion into a passage formed in an object according to the present invention comprises an elongated fastener shaft having a proximal end and a distal end and a fastener head attached to the proximal end of the shaft. The fastener head has opposed distal and proximal surfaces and is configured for manipulation of the fastener for installation and removal. The tamper-evident fastener also comprises an elastomeric sleeve formed around at least a portion of the fastener head. The elastomeric sleeve is formed from a thermoshrinkable material and is configured so that upon application of sufficient heat the elastomeric sleeve will shrink to establish a tamper-evident appearance and conform to at least a portion of the fastener head. This secures the elastomeric housing to the fastener and assures that substantial subsequent manipulation of the fastener for removal of the fastener causes a visually apparent change in the tamper-evident appearance of the elastomeric sleeve.
The elastomeric sleeve of a tamper-evident fastener according to the present invention may be formed as a cylindrical tube having a central passage with a diameter sufficient to accommodate at least partial insertion of the fastener head into the central passage. At least a portion of the elastomeric sleeve may be formed adjacent the distal surface of the fastener head to provide an intermediate layer between the fastener head and a surface surrounding the passage when the fastener shaft is inserted into the passage of the object. At least a portion of the fastener shaft of a tamper-evident fastener of this invention may be threaded for mating with a threaded portion of the passage. The fastener may be configured to prevent a fluid from migrating through the passage. Optionally, when the passage is a through hole at least a portion of the shaft may be threaded for mating engagement with a threaded female coupling.
The elastomeric sleeve of the tamper-evident fastener of this invention may be formed and configured so that after thermal shrinkage the sleeve will remain secured to the fastener upon subsequent exposure to temperatures up to at least about 250° F. The elastomeric sleeve may be formed so that after thermal shrinkage the sleeve may remain secured to the fastener upon subsequent contact with a petroleum product.
Another embodiment of the present invention is a tamper-evident sleeve for application to a fastener having a fastener shaft and a fastener head with opposed distal and proximal surfaces wherein the fastener head is attached to one end of a fastener shaft. The sleeve comprises an elastomeric housing defining a central cavity and at least one opening into the central cavity. The central cavity and the opening. are configured to accommodate at least partial insertion of the fastener head into the central cavity. The elastomeric housing is formed from a thermoshrinkable material and is configured so that upon application of sufficient heat, the housing will shrink to establish a tamper-evident appearance and conform to at least a portion of the fastener head. This secures the elastomeric housing to the fastener and assures that substantial subsequent manipulation of the fastener will cause a visually apparent change in the tamper-evident appearance of the elastomeric housing.
The elastomeric housing of the tamper-evident sleeve of this invention further may be formed as a cylindrical tube. At least a portion of the elastomeric housing of the tamper-evident sleeve of this invention may be formed adjacent the distal surface of the fastener head to provide an intermediate layer between the fastener head and a surface of an object forming a passage into which the fastener is inserted.
The elastomeric housing may be formed and configured so that after thermal shrinkage it will remain secured to the fastener upon subsequent exposure to temperatures Up to at least about 250° F. Additionally, the elastomeric housing may be formed and configured so that after thermal shrinkage it will remain secured to the fastener upon subsequent contact with a petroleum product.
A method of installing a tamper-evident fastener into a passage formed in an object according to the present invention comprises providing a fastener having an elongated fastener shaft with a proximal end and a distal end, and a fastener head attached to the proximal end of the fastener shaft. The fastener head has opposed distal and proximal surfaces and is configured for manipulation of the fastener for installation and removal. The method of installing a tamper-evident fastener of this invention further comprises the step of providing an elastomeric sleeve formed around at least a first portion of the fastener head. The sleeve has an elastomeric housing defining a central cavity and at least one opening into the central cavity. The elastomeric housing of the sleeve is formed from a thermoshrinkable material and configured and disposed around the at least a first portion of the fastener head. Upon application of sufficient heat, the elastomeric housing shrinks to establish a tamper-evident appearance and conform to at least a second portion of the fastener head to secure the elastomeric housing to the fastener and to assure that substantial subsequent manipulation of the fastener for removal of the fastener causes a visually apparent change in the tamper-evident appearance of the sleeve. The method of installing a tamper-evident fastener of this invention further comprises the steps of inserting at least a portion of the fastener head into the central cavity of the elastomeric housing of the sleeve, inserting the elongated fastener shaft into the passage formed in the object, and applying heat to the thermoshrinkable sleeve sufficient to shrink the thermoshrinkable sleeve to substantially conform with the at least a second portion of the fastener head.
A portion of the elongated shaft provided in a method according to the present invention may be threaded for mating with a threaded portion of the passage. Additionally, the fastener may

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