A CURING APPARATUS

Abstract: A curing apparatus is disclosed, comprising a housing (1), in which is mounted an ultra-violet radiation source (3), the housing (1) also supporting an inner casing (2), which is spaced from the housing (1) and supports a dichroic reflector means (5), the reflector means consisting of at least one sheet of glass-like dichroic material arranged in the inner casing (2) in such a manner as to reflect ultra-violet radiation from the source (3) striking it back towards a material to be treated, the inner casing (2) supporting the reflector means (5) in such a way as to enable an air flow to be induced in a space (7) between the inner casing (2) and the reflector means (5). The reflector means (5) may be rotatable about the radiation source (3) into a position in which the source is shielded from the material being treated.

Description: A Curing Apparatus This invention relates to a curing apparatus, for example for curing materials such as synthetic plastics, printing inks, resins or the like, by means of an ultra¬ violet radiation source. Hitherto, such an apparatus has consisted of an ultra¬ violet source, disposed in a semi-circular or parabolic reflector, the source being directed at the material to be cured so that the required curing is accomplished during the necessary time. The process may be performed either on a continuously moving material supported, for example, on a conveyor or in an intermittent manner, the ma.terial dwelling in the treatment region or zone for the requisite time. As examples of the materials which can be treated are webs of synthetic plastics, or of paper, or of some other base, coated with a synthetic resin, the plastics or the resin requiring to be cured by the use of ultra-violet radiation. A particular problem associated with the known apparatus is, apart from the ultra-violet radiation which is used to effect the curing, a large and undesirable amount of infra-red radiation is also generated, accompanied by unacceptable amounts of heat. The present invention seeks to provide an apparatus which overcomes the disadvantages of the known apparatus . According to the invention, a curing apparatus consists of a housing in which is mounted an ultra-violet radiation source, the housing also supporting an inner casing which is spaced from the housing and supports reflector means, the reflector means consisting of at least one sheet of dichroic material arranged in the inner casing in such a manner as to reflect ultra-violet radiation from the source striking it back towards the material to be treated, the inner casing supporting the reflector means in such a way as to enable an air flow between the inner casing and the reflector means. Means are also provided to provide an air flow between the interior of the housing and the inner casin . In a second embodiment of the invention, the inner casing is rotatable about the ultra-violet radiation source, into a position in which it forms a shield between the source and the material to be subjected to the radiation. The reflector means comprises at least one panel of a transparent, glass-like material which reflects ultra-violet radiation but which allows infra-red radiation and the accompanying heat to pass through it. The material of the reflector means may be a ceram, or a borosilicate glass, provided with a coating so that the reflector means is in the form of a dichroic reflector. In another embodiment of the invention, the reflector means may comprise two reflectors shaped as half parabolas as seen from one end. The ultra-violet source is typically an elongated element, the reflector means extending along the length of the source, between the source and the inner casin . The housing is preferably arranged to extend over a treatment region or zone, along which the ultra-violet source extends with the associated reflector means; the inner casing is provided on its inner surface, facing the reflector means with a heat-absorbing coating " or surface. An embodiment of the invention will now be described by way of an example and with reference to the accompanying drawings in which: Figure 1 shows, in diagrammatic form, a cross-section of the apparatus, and Figure 2 is a diagrammatic, partly cut-away perspective view of the apparatus as seen from below. In its simplest form the apparatus consists of an elongated housing 1 which is generally trough- or channel- shaped and is arranged to extend over a treatment region or zone, for example above a conveyor belt. The length of the housing 1 is determined by the dimensions of the material to be radiated and the time for which it must remain in the treatment region. In certain instances, the housing may be several metres in length. Supported inside the housing 1 in such a manner as to provide a space between it and the housing, is an inner casing 2, which is in the form of a semi-circular trough extending along the housing and treated on its inner surface with a heat-absorbing material or coating. The outer surface of the inner casing 2 may be provided with heat-dissipating ribs or fins 8 and is made, for example, from an aluminium extrusion or casting. Disposed in the central region of the housing 1 and extending along the interior of the inner casing 2 is an ultra-violet radiation source 3, supported at least at each end by suitable fittings. At each end of the inner casing is an end panel member 4. Intermediate supports may be provided if the length of the source so requires. The end panel members 4 form the ends of the inner casing 2 and also, with the casing, support the reflectors δ which are arranged in the casing in such a manner as to reflect ultra-violet radiation from the source 3 back down to the treatment zone or region. The reflectors δ are preferably made of flat sheets of a transparent, glass-like material such as a ceram or borosilicate glass, coated to form dichroic reflectors. However, they may also be in the form of half-parabolic sections, where the focusing of the reflected ultra-violet radiation needs to be improved. Infra-red radiation and the associated waste heat passing through the reflectors δ enters the space 7 between the reflectors and the interior of the inner casing 2 from where it is extracted by a cooling air flow. Cooling air is also arranged to pass through the space 6 between the outer surface of the inner casing 2 and the interior of the housing 1, the ribs or fins 8 on the inner casing 2 assisting in the transfer of heat. As an example of the operating conditions for the apparatus, an ultra-violet source used to cure such materials as synthetic plastics or resins is rated at a power of some 80 Watts for each centimetre of its working length, so that for a long tubular source, the amount of heat that would be generated largely by the infra-red radiation could damage the material being treated. The use of a dichroic material such as a suitably- coated transparent glass-like material for the reflector means enables the major proportion of the reflected ultra¬ violet radiation to be redirected back to the treatment region, while the major part of the infra-red radiation impinging on the reflectors passes through the reflectors, so reducing the amount of heat being directed into the treatment region. In a second and particularly advantageous embodiment of the invention, the inner casing 2, with the reflector means δ is arranged to be able to rotate about the longitudinal axis of the source 3, into a position where the casing 2 provides a shield between the source and the material being treated. Eotation is obtained, for example, by means of an electric motor, driving the inner casing through a clutch, limit switches being provided to control the amount of rotation.. Preferably, one end of the inner casing is provided with a split bearing 9, which enables the casing to revolve around the source, while . at the same time facilitating the replacement of the source in the event of a failure. Tests ' have indicated that as much as 90% of the ultra¬ violet radiation striking the reflector means can be directly transmitted or reflected into the treatment region, while a similar percentage of the infra-red radiation and associated heat impinging on the reflector means escapes into the intermediate space between the reflector means and the inner casing, to be extracted. Additional cooling is applied to the space between the interior of the housing and the inner casing to amplify the cooling effect. As a result, the treatment of materials in the. treatment region or zone can be effected under conditions of reduced temperature in the treatment zone, so reducing the risk of damage to the material or any supporting substrate or member, irrespective of whether the process is carried out continuously or intermittently.

Claims: CLAIMS 1. A curing apparatus comprising a housing in which is mounted an ultra-violet radiation source, the housing also supporting an inner casing which is spaced from the housing and supports reflector means, the reflector means consisting of at least one sheet of dichroic material arranged in the inner casing in such a manner as to reflect ultra-violet radiation from the source striking it back towards the material to be treated, the inner casing supporting the reflector means in such a way as to enable an air flow between the inner casing and the reflector means. 2. Apparatus according to Claim 1, wherein means are provided to generate an air flow between the reflector means and the inner casing. 3. Apparatus according to Claim 1 or Claim 2, wherein the inner casing is rotatable about the ultra-violet radiation source, into a position in which it forms a shield between the source and the material to be subjected to the radiation. 4. Apparatus according to any one of claims 1 to 3, wherein the reflector means comprises at least one panel of a transparent, glass-like material which reflects ultra-violet radiation but which allows infra-red radiation and the associated heat to pass through it. δ. Apparatus according to any one of Claims 1 to 4, wherein the reflector means is in the form of a dichroic reflector. 6. Apparatus according to any one of the preceding claims, wherein the reflector means may comprise two reflectors shaped as semi-parabolic sections, as seen from one end. 7. Apparatus according to any one of the preceding claims, wherein the inner casing is provided on its inner surface, facing the reflector means, with a heat-absorbing coating or surface. 8. A curing apparatus, comprising an elongated housing which is generally trough- or channel-shaped .and is arranged to extend over a treatment region or zone, the length of the housing being determined by the dimensions of a material to be treated and the time for which it must remain in the treatment region, the housing supporting an inner casing in such a manner as to provide a space between it and the housing, said inner casing being in the form" of a semi¬ circular trough extending along the housing and treated on its inner surface with a heat—absorbing material or coating, the central region of the housing having an ultra-violet radiation source extending along the interior of the inner casing, is an ultra-violet radiation source, each end of the inner casing having an end panel member which forms an end panel of the inner casing and also, with the casing, supports dichroic reflector means which are arranged in the casing in such a manner as to reflect ultra-violet radiation from the source back down to the treatment zone or region, a space being provided between the inner casing and the reflector means through which a cooling airflow can be induced. 9. Apparatus according to Claim 8, wherein the reflector means comprise a transparent, glass-like material coated to form a dichroic reflector.

Inventors: POLLOCK GERALD, POLLOCK, GERALD
Applicants: FLUID DYNAMICS SALES LTD, FLUID DYNAMICS (SALES) LTD
Application year: 1990
Main classification: B05D3
IPC codes: B01J19, F26B3