Radiant energy – Radiation controlling means – Shields
Reexamination Certificate
1998-11-23
2001-08-21
Anderson, Bruce C. (Department: 2881)
Radiant energy
Radiation controlling means
Shields
C250S515100
Reexamination Certificate
active
06278125
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a shielded radiation assembly for protecting operating personnel from the exposure to potentially harmful radiation. More specifically, the invention relates to a radiation shield for a radiation emitting device that allows easy access to the radiation treatment space while minimizing radiation leakage.
BACKGROUND OF THE INVENTION
The controlled radiation of plastics results in the cross-linking of polymer chains and, thereby, provides desirable characteristics to products made from the plastics. It is well known in the plastic films industry that radiation treatment strengthens a film. Various types of coatings are also treated with radiation to improve the bonding of the coating to the object that is being coated. In addition, various adhesive materials are exposed to radiation to promote the curing. This is especially important in production line manufacturing, where the fast curing of an adhesive is required so that the article being produced can be expeditiously moved to the next stage in the production sequence.
A particularly useful form of radiation treatment in manufacturing applications is ultraviolet (UV) curing. UV curing is an electrically based technology which uses ultraviolet radiation generated by a high voltage power supply to rapidly convert certain photo-reactive materials from liquids to solids. These ultraviolet-curable materials include, inks, coatings and adhesives. Although these materials are liquids in their uncured state, they contain no volatile organic compounds (VOCs) and, thus, avoid one of the more serious problems encountered when organic compounds (VOCs) and, thus, avoid one of the more serious problems encountered when using solvent-based adhesives, i.e., the safe venting and treatment of the VOCs before releasing them into the atmosphere.
Polymer-based adhesives are used extensively in many industries, such as the automotive industry, the medical industry, and the electronics industry, as the most efficient means of joining two or more elements. The inherent disadvantage of the use of adhesive is the time factor for setting or curing the adhesive. Air dried adhesives can take from several minutes to several hours to cure and, as a result, make it difficult to implement continuous manufacturing processes. In order to solve this problem, certain polymer-based adhesives have been developed, which cure at an accelerated rate when subjected to ultraviolet radiation. Ultraviolet radiation curing is a process which involves polymerization, or cross linking of monomers upon exposure of the monomer to ultraviolet radiation. For monomers that do not polymerize when exposed to ultraviolet radiation, a sensitizer is added which absorbs ultraviolet energy and initiates a polymerization reaction in the monomer. The use of ultraviolet radiation provides significant processing and handling advantages during manufacture by instantly immobilizing the resin. Immobilization of the resin is controlled to provide sufficient gelation to prevent flow out of the part but allow good wetting between layers, thus assuring even resin distribution, reduced void formation and ease of handling of the finished part without resin migration, sagging or dripping. In addition to a substantial saving of time, there is also a considerable saving in plant space, since an ultraviolet curing line is faster and considerably shorter than previous systems which utilized other means for accelerating the curing of adhesives, such as ovens. Another advantage of ultraviolet cured adhesives over solvent-based adhesives is that the radiation treatment does not discharge volatile organic compounds into the atmosphere.
While UV curing addresses certain industrial needs, there are safety concerns involved with the use of ultraviolet radiation curing systems. Serious bums to the skin and eyes can be caused by the high intensity of the ultraviolet radiation if adequate shielding in not provided. This problem is complicated by the fact that ultraviolet bums are not felt for several hours, so that serious injuries can occur without the person realizing that the injury is occurring. In addition, a considerable amount of infrared energy is produced by the ultraviolet emitting device which can be harmful to personnel and can damage the products which are treated by the ultraviolet radiation. Although prior art devices provide shields to protect individuals from ultraviolet radiation, these shields are not always effective because manufacturing requirements necessitate that the equipment be designed to allow easy and continuous access to the radiation zone. As a result, many of the shields do not always totally enclose the radiation zone and a certain amount of radiation escapes the system. In other cases, the shields are not adjustable and do not allow the equipment to be used for a variety of different applications.
SUMMARY OF THE INVENTION
The present invention provides a shielded radiation assembly that includes a support structure. The support structure supports a radiation shield. A radiation emitting device is moveably supported on the support structure for independent movement with respect to the radiation shield. The shield defines an enclosed space about the radiation emitting device for protecting against radiation leakage.
In preferred embodiments of the present invention, the support frame includes a base for supporting an object which is to be subjected to radiation. An upright support member extends from the base and supports both the shield and the radiation emitting device. The radiation emitting device is movable along the upright support member with respect to the base to vary its position with respect to the object. The shield may also be movable with respect to the base to raise and lower the shield to provide access to the enclosed space.
The support structure may also support one or more cooling fans. The fans may be positioned so as to dissipate heat generated by the radiation emitting device.
Preferred radiation emitting devices include radiation emitting devices that emit actinic radiation, including ultraviolet and visible light.
Preferred shields can be made from a variety of materials, including radiation absorbent materials, radiation reflective materials and metal coated materials.
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Anderson Bruce C.
Hoffmann & Baron , LLP
Loctite Corporation
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