Ink Drying Reflector System

Abstract

The invention relates to a radiator in which there is an elliptical reflector, part of which is formed by two spaced apart plates forming ducting, the ducting being pivotable from a first, open, position to a second position in which the radiation from the radiator is cut-off, cooling fluid being drawn through the ducting to cool the reflector.

Description

The invention relates to radiator fittings and to apparatus for cooling a fittings housing, for example, arc discharge tubes, particularly those with a high rating. Such fittings are often used for drying printing inks on paper or other materials.

At the present stage of development of ultra-violet ink dryers for printing it is necessary to use a high intensity arc (for example 200 watts per inch) and to focus the power of the arc in a concentrated area on a moving substrate with the printing ink thereon.

A serious drawback to this prior arrangement is that the Infra-Red content of the radiation emitted from the tube is also focussed and the heat concentration is such that if the paper should stop or even slow down, it often ignites.

Any barrier interposed between the radiator and the substrate will likewise be subjected to a degree of heat concentration depending on its distance from the radiator and from the focussing point on the substrate. This concentration 0of heat is likely at best to seriously distort the barrier.

Also, because of the limited space available in the majority of installations, it is necessary that any shutter or barrier takes up minimal space.

Because of the time lag in restarting the arc when extinguished, it is considered undesirable to switch off the arc to overcome the above problem.

According to the invention there is provided apparatus for cooling a radiator fitting, comprising ducting which is adapted for movement to a position in which radiation from the radiator is substantially cut off and in which cooling fluid passes through the ducting so that the fitting is cooled.

In a preferred embodiment the ducting may comprise a first plate comprising part of a reflector for the radiator and a second plate spaced from the first plate by a diaphragm, the two plates being closer together at an inlet for the cooling fluid than at an outlet for the cooling fluid.

The radiator may be an arc tube mounted in a housing and situated within an elliptical reflector, the first plane comprising a part of the reflector. Moreover, the reflector may include perforations to enhance cooling of the fitting.

In a position in which radiation from the radiator is not cut off, the ducting may preferably by situated adjacent a wall of the housing, and in the second position cooling fluid, which may be air, may also pass through the ducting. The ducting may move by pivoting between the two positions on a pivot pin extending longitudinally along the housing in a direction substantially parallel with the arc tube.

A suitable radiator temperature is maintained in the closed position so that the radiator may return to full power when the ducting is retracted to the second position. One means of achieving this is to reduce the power into the radiator in the closed position. Alternatively the ventilation may be increased or a combination of both methods may be utilized.

The ducting may be controlled automatically so that the radiator may be enclosed and the radiation cut off when substrate moving beneath the radiator stops or slows down, so that heat damage to the substrate may be substantially obviated. This is particularly so when the radiator is used to dry ultra violet sensitized printing ink impressed on paper or other substrate moving in the focussed energy of the reflector, in which case ultra-violet energy from the radiator causes drying or curing of the ink.

One embodiment of the invention is diagrammatically illustrated, by way of example in the accompanying, wherein:

FIG. 1 shows a transverse cross-section through a radiator fitting used to dry printing ink on paper passing below the fitting, and FIG. 2 shows a fragment of FIG. 1 and discloses a possible modification of the present invention.

The radiator fitting 1 includes a radiator 2 which comprises a 5 KW arc tube, two feet long and emitting ultra-violet energy, mounted in a housing 3 which has an inlet 4 for cooling air and an extraction duct 5 for the air. The extraction duct 5 is in connection with a suction fan 18. The housing 3 includes an elliptical reflector 6 of high polished anodized aluminium. The reflector comprises a fixed upper section 7 and two side wall sections 8. Each side wall section forms a first plate of a cooling duct 9 and is spaced apart from a second plate 10 by a diaphragm or spacer 11. The mouth 12 of each cooling duct is approximately one ince across and is narrower than the exit, which is a communication with the extraction duct 5.

Each cooling duct is pivotably mounted on a pivot pin 13 extending the length of the housing and is capable of pivoting from a first position, shown in heavy lines in the drawing, in which the respective cooling duct is hinged inwardly to cut off substantially the radiation emitted from the radiator 2 and a second position, shown in faint lines, in which the cooling ducts are adjacent a wall of the housing, the first plate of each duct then forming part of the elliptical reflector. In the second position, the path through each cooling duct is partially obstructed by a flange 14 on the housing. Moreover, the reflector may have perforations (not shown) which facilitate cooling.

Use of the apparatus is described assuming the radiator 1 is used to dry printing ink impressed on paper (not shown) passing through the focussed energy 15 of the elliptical reflector, as shown by the arrows X.

Assuming the printing machine is functioning normally, the cooling ducts 9 are in the second position shown by faint lines, and the radiator is emitting ultra-violet energy at full power to dry the ink. Cooling air is sucked into the lamp housing around the flanges 14 and through the ducts 9 to the extraction duct 5.

If the paper now slows down or stops, a sensor, for example a minimum paper speed sensor or a heat sensor, is actuated to operate a motor, solenoid, hydraulic means or any other suitable means, which rotates the cooling ducts 9 to the closed position shown in heavy lines so that radiation from the radiator is cut off, while cooling air is drawn through the cooling ducts, over the reflector and out through the extraction duct. Cooling air also enters the triangularly shaped tunnel "E" formed by the closed ducts 9 and the section 7, and through the perforations if utilized. Air escapes from the tunnel "E" through the perforations, and through gaps "D."

The cooling ducts thus function to shut off the energy and to cool the fitting. Moreover, when the ducts pivot inwardly to the first position, they may automatically actuate a switch to reduce the power of the radiator, while at the same time the tunnel causes the temperature of the arc to be maintained to permit immediate operation when the cooling ducts are returned to the second position.

When the paper or substrate is again moving at a sufficiently high speed, the cooling ducts are retracted to the walls of the housing and the radiation again falls on the paper or substrate. Simultaneously and instantaneously the radiator is stepped up to a suitable operating power.

The first plates 8 of each cooling duct 9 may include flexible seal strips, as shown at 16, and there may be a seal 17 between the cooling ducts and the housing as shown in FIG. 2.

The invention thus provides the following advantages: 1. Compact arrangement. 2. Using Reflector as shutter saves space and eliminates other parts. 3. Closing of reflector de-focuses a large area of the reflective surface and therefore spreads heat more evenly. 4. Movement of air path with shutter ensures adequate surface cooling in closed position.

Claims

I claim:

1. Apparatus for cooling a radiator fitting used for drying a web, comprising a housing, reflector means and radiator means, the radiator means being housed in the housing and enclosed by said reflector means which is also wholly in the housing, and extraction duct means including a first part communicating with extraction fan means and with the interior of the housing between said housing and said reflector means, and including in said housing pivot means extending substantially parallel to the radiator means, parts of said reflector means being pivotable on respective ones of said pivot means, said pivotable parts of said reflector means each comprising a first plate means and a second plate means spaced therefrom to form a further part of said extraction duct means having inlet means and outlet means, which outlet means communicates with said first part of said extraction duct means and through which cooling air can flow from said inlet means to said outlet means, said pivotable parts of said reflector means being movable from a position adjacent said housing to a position in which radiation from said radiator means is substantially cut off with said cooling air being freely flowable through said pivotable reflector parts in both of said positions.

2. Apparatus as defined in claim 1, wherein said inlet means is of less dimension between said first plate and said second plate than is said outlet means.

3. Apparatus as defined in claim 1, wherein said reflector means is elliptical and said first plate means forming part of the reflective surface of said reflector means.

4. Apparatus as defined in claim 3, wherein there is flexible strip means, said flexible strip means being secured to edge means of said first plate means.

5. Apparatus according to claim 1, wherein said reflector means includes a stationary center portion, said parts each being tubular and being disposed on opposite sides of said center portion, and said pivot means defining pivot axes located closely adjacent the opposite edges of said center portion.

6. A reflector-type dryer, particularly for drying a moving web, comprising:

housing means defining therein a chamber open at one end;

curved reflector means positioned within said chamber and having an inner concave reflective surface directed toward the open end of said chamber;

said reflector means including a first portion stationarily positioned relative to said housing means and a second portion pivotally mounted relative to said first portion for swinging movement between an open reflective position and a closed position wherein said second portion and the remainder of said reflector means form a substantially closed tunnel-like compartment, said second portion being positioned wholly within said chamber when in said open and closed positions;

radiator means disposed within said chamber in front of said reflective surface, said radiator means being positioned so as to be within the tunnel-like compartment when said second reflector portion is in said closed position;

a cooling system for said dryer including an exhaust duct;

said second reflector portion including first and second spaced walls which are fixed relative to one another and define therebetween a duct which is part of said exhaust duct of said cooling system and has inlet and outlet openings adjacent the opposite ends thereof for permitting flow of cooling fluid therethrough, the inlet opening being disposed closely adjacent and directed substantially toward the open end of said chamber, and one of said walls constituting a portion of said reflective surface when said second reflector portion is in said open position; and

said housing means including wall means defining a stationary part of said exhaust duct communicating with a portion of said chamber adjacent the outer surface of said reflector means, said outlet opening associated with said second reflector portion communicating with said portion of said chamber.

7. A dryer according to claim 6, wherein said reflector means includes a third reflector portion disposed wholly within said chamber and pivotally mounted relative to said first portion for swinging movement between an open reflective position and a closed position, said first reflector portion being disposed between said second and third reflector portions whereby said second and third reflector portions are swingable toward one another as they are moved toward their respective closed positions, said three reflector portions coacting to form said closed tunnel-like compartment.

8. A dryer according to claim 7, wherein said third reflector portion also includes first and second spaced walls fixed relative to one another and defining a duct therebetween having inlet and outlet openings adjacent the opposite ends thereof, the inlet opening of said latter-mentioned duct being disposed adjacent and directed substantially toward the open end of said chamber and the outlet opening of said latter-mentioned duct communicating with said portion of said chamber.

9. A dryer according to claim 8, wherein said second reflector portion is mounted for swinging movement about a hinge axis located closely adjacent one edge of said first reflector portion, wherein said third reflector portion is mounted for swinging movement about a hinge axis located closely adjacent the other edge of said first reflector portion, and wherein the outlet opening associated with each of said second and third reflector portions is located closely adjacent the respective edge of said first reflector portion.

10. A dryer according to claim 7, wherein each of said second and third reflector portions comprise elongated tubular members having said inlet opening defined adjacent one end thereof and said outlet opening defined adjacent the other end thereof, each of said tubular members defining said duct extending therethrough, the inlet opening defined adjacent the one end of said tubular member being positioned closely adjacent the open end of said chamber, and the outlet opening defined adjacent the other end of said tubular member being disposed closely adjacent said first reflector portion and communicating with a portion of said chamber located rearwardly of said first reflector portion.