JPS607796Y2 - A device that cures three-dimensional objects with ultraviolet light without rotating them. - Google Patents

Description

[Detailed description of the invention] This invention cures three-dimensional objects by irradiating ultraviolet rays (cu
The present invention relates to a device for curing the object uniformly without rotating the object.

In recent years, the graphic arts and packaging industries have turned their attention to a process termed ultraviolet curing to solve the twin problems of stringent radiation control standards and energy conservation in the drying of inks and coatings.

Curing is accomplished by a UV-initiated polymerization reaction that changes the components of the ink or coating almost instantaneously from a liquid to a solid state.

Since these inks and coatings do not contain solvents, they provide essentially stain-free printing.

As will be seen below, in order to provide maximum intensity radiation, lamps for UV curing are typically highly focused units.
, and the substrate to be cured is placed in the focal plane.

This device works well for hardening flat or planar surfaces, but also works well for collapsible metal tubes and hard plastic containers and two-piece (i.e. seamless drawing and ironing) hardening.
ss drawn and wall-ironed)
) Curing of cylindrical objects such as beverage and beer cans requires a more complex mechanical system that rotates the article to effect curing over the entire cylindrical surface.

The need to rotate cylindrical objects such as cans poses several problems which are obviated by the present invention.

This can be closely related to the use of rotating mandrel pins, brush pins, error turbines or suction cups.

In any case, the equipment for rotating the cans is expensive and does not necessarily provide trouble-free operation.

When the can is assembled, it becomes unstable and falls off the pin or brush used to rotate it.

All of these problems of reliability, can stability, and wear become even more acute at the high production line speeds continually demanded by industrial users.

Furthermore, conventional two-piece canlines do not have the necessary equipment to rotate the cans, and therefore, if it is desired to convert a conventional two-piece canline to a UV curing mode, it is necessary to provide the necessary rotation. It is necessary to substantially modify the can-operated portion of the line after the decorator to make it so.

This involves additional cost and complexity, which is avoided in accordance with the present invention.

Therefore, an object of the present invention is to provide an apparatus for curing a three-dimensional object by irradiating it with ultraviolet rays without rotating the object.

A further object of the invention is to provide an apparatus for curing two-piece cans and other cylindrical objects by UV radiation without rotating the can.

It is a further object of the present invention to provide an apparatus that provides uniform curing in both the axial and azimuthal directions of the can at conventional two-piece line speeds and uses a relatively small number of lamp units.

The invention will be better understood with reference to the accompanying drawings.

Referring to FIG. 1, a typical light beam used for ultraviolet curing consists of a reflector and a light bulb.

The reflector focuses the light rays from the bulb.
Used to provide high strength on inks or coatings to be polymerized.

This is done because the curing rate of many inks and coatings is dependent on the peak intensity of the ultraviolet radiation, and most such materials exhibit an intensity threshold beyond which effective curing will not occur.

Typically, the reflector is semi-elliptical in cross-section, and the bulb is along the focal point of that cross-section.

The substrate on which the UV curable ink or coating has been applied passes through the other focal point of the ellipse.

This device, shown in cross section in FIG. 1, ensures that the light rays from the bulb reflected from the semi-ellipse are directed to other, near-focal areas.

This creates a relatively narrow strip (typically 112# wide) of high intensity light the length of the bulb on the substrate.

Although the techniques described above serve extremely well in curing UV-polymerizable inks or coatings on flat or planar surfaces, curing of such inks and coatings on multi-sided objects requires more complex equipment. do.

One such application of considerable commercial importance involves the curing of inks and coatings on the cylindrical outer surface of two-piece cans.

Such cans, widely used for beverages and beer, are first formed from a single piece of metal that is stamped into the shape of a cup and drawn out into a cylinder with a closed bottom.

The two-piece is the top that is added after the can is filled.

The can is coated and printed on the side walls of its cylindrical outer surface by a special printing machine.

Such a can is shown in FIG. 2, where the printing is simply represented by the letter A on the outside of the can.

After decoration, if a UV curable ink or coating is used, the can must be exposed to high intensity UV light over its entire exterior sidewall.

The technique currently used for curing inks and coatings on cylindrical two-piece cans is illustrated in FIG.

The can 1 is supported on a belt or pin or brush 3 attached to a moving chain 2, and is supported by a long lamp 4,
5 or a strip of ultraviolet light generated by the lamp passes through a short row of lamps arranged almost perpendicular to the axis of the can.

The lamps are tilted at a slight angle (θ) to the vertical so that the strip of light rays covers the top of the side wall at one end of the lamp array and the bottom of the side wall at the other end.

As the can is translated under the ramp, the mantle pin or brush is caused to rotate by mechanical means, thereby causing the can to rotate.

The principle is to rotate the can fast enough to expose all parts of the printed area to high-intensity ultraviolet radiation concentrated in the vicinity of the second focal point of the elliptical reflector.

This results in the spiral curing pattern shown in FIG. 4 in which each strip 1, 2, 3, etc. is cured one after the other as the can rotates under the lamp.

Although the above technology is in commercial use, it has distinct drawbacks, and the present invention is designed to overcome this drawback.

In particular, the requirement that the can be rotated posed the problems listed above.

The present invention closely resembles the same results as prior art systems without the mechanical and economic problems caused by rotational demands.

Aspects of the invention are illustrated in FIGS. 5-7.

The can 14 is moved along a translational path by a pin 13 mounted on a chain 12 driven by a motor 10.

Unlike the prior art system shown in FIG. 3, the transport belt or pin chain 12,13 is of the type found in conventional can lines and the pin 13 does not rotate.

A focused UV lamp unit 15, 16, consisting of a housing containing a reflector and a lamp tube 16, is arranged on the l side of the translational path facing the path, and the focused UV lamp unit 15. 18.
Reference numeral 17 is arranged on the other side of the translation passage facing the translation passage so that the can moving between the lamp units is illuminated by the light beams from both lamp units.

As shown in FIG. 6, each pair of lamp units is mounted such that their focal planes are parallel to each other.

However, unlike the prior art system of FIG. 3 where the closest surface of the can is located at the focal plane, in embodiments of the present invention the can is located substantially closer to the lamp unit than the focal plane. There is.

FIG. 8 depicts the prior art in which the nearest region of the can is at or near the focal plane, and FIG. 9 depicts the present invention in which the can is substantially closer than one or more focal planes. It is clearly explained by comparison with the figures.

Thus, in FIG. 9, the point 1 closest to the lamp unit 1 is substantially closer to the lamp unit than the focal plane 1, and the point 2 closest to the lamp unit 2 is substantially closer to the lamp unit than the focal plane 2. substantially closer.

In the experimental embodiment of the invention, the can has a diameter of 21/2
”, and points 1 and 2 are 3 points from the corresponding lamp unit.
73" and the focal plane is located 2114" from the lamp unit.

The unique device of the present invention uses the unfocused light rays emitted by the lamp by positioning the can substantially closer to the lamp unit than the focal plane, which Provides curing over a larger area of a three-dimensional object than a light beam.

Thus, in FIG. 10 it can be seen that the area covered by the unfocused rays obstructed by the surface of the can is larger than the area that would be obstructed by the focused rays.

The fact that there is less light per unit area in area a is offset to an extent by the fact that the surface of the can is closer to the light source, resulting in a higher energy intensity for effective curing.

The present invention also utilizes isotropic light beams generated from the length of the lamp and reflector to effectively cure three-dimensional objects.
pic rays).

Thus, referring to FIG. 11, every point along the lamp bulb emits light isotropically, and there are many rays of light direct and reflected from the bulb incident on the can at different angles.

These rays are used to cure the "sides" of the can, and are the reason why only two lamp units can cure an area extending 360° around the can.

As noted above, to be commercially acceptable, the cure imparted must be uniform around the surface of the can;
and must be achievable at conventional line speeds without the use of a reasonably large number of light sources.

This is achieved by pairing lamp units in the azimuthal range (az
This means that the axial area of the surface to be hardened over the entire 3600 imthal extent should be as large as possible and must be hardened as uniformly as possible.

This is the long dime direction of the lamp unit.
nsions) are oriented at a small angle with the direction of translation, and each lamp unit is angularly offset from the direction of translation in a direction opposite to the other lamp unit of the pair.
fset).

Therefore, in FIG. 5, lamp units 18, 17 and 1
6.15 are angularly offset in opposite directions from the direction of translation, and in one embodiment each of the lamp units is offset by 6° from the direction of translation.

Although this angle can be varied to get the best results and be optimized in industrial applications, 12
Do not exceed °.

As shown in FIG. 5, the lamp units of each pair intersect each other approximately at their midline such that the pair is symmetrical about the mid-line.

The lamp unit may be mounted for proper positioning by mechanical means, and various such mounting means will occur to those skilled in the art and do not form part of the present invention.

However, by way of example, platform 30 is shown in FIG. 7 and can be seen to have supports 31 and 32 projecting perpendicularly from platform 30 for mounting lamp units 18, 17 and 16, 15, respectively.

If the pairs of lamp units are mounted parallel to each other and parallel to the direction of can movement (i.e. without angular deviation), surface hardening in the 360° azimuth range and moderate axial range is achieved. Ru.

This is satisfactory for many applications where hardening of additional axial areas, distantly related to small angular offsets, is not of significant benefit.

The relative dimensions of commercially available light sources and commercially available cans useful in practicing the present invention are such that a pair of lamp units stiffens the azimuthal strip only along a portion of the axial region of the can. Because of the size, more than one pair of lamp units may be required to cure the entire surface of the can.

As shown in FIG. 5, a second and more pairs of lamp units are optionally provided, each pair being axially offset from the adjacent pair and extending several times along the axis of the can. gives overlapping azimuthal hardening strips.

Using a pair of 10" long ultraviolet lamp units, a 3" axially extending strip at a typical line speed of 1 min. Cured for cans moving more than 300 feet per inch.

Thus, a system for curing a typical 6" high can would require only two pairs or a total of four lamp units, whereas a system for curing a typical 6" high can would require only two pairs or a total of four lamp units, whereas a 6" lamp unit as shown in FIGS.
A row of 2 lamps would be able to cure the can line at 350 feet per minute with overlap in the cured strips.

This line speed corresponds to the industry standard of 80 cans per minute when using a pin-chain with 5174'' spacing between pins.

A further aspect of the invention is shown in FIG.

Referring to FIG. 12, it can be seen that the pin chain 50.51 transports the can 52 past the lamp unit.

According to the first embodiment, the lamp unit is parallel to the direction of can movement or slightly angularly offset with respect thereto.

However, instead of pairs of lamps facing each other, each lamp unit of the embodiment of FIG. 12 faces a reflector.

Therefore, the lamps 53, 55 and 57 have respective reflectors 54,
Facing 56 and 58.

A reflector that is approximately parabolic in cross-section and wider but shallower than the elliptical cross-section reflector used in the lamp unit itself faces directly into the lamp unit and is placed very close to the non-illuminated side of the can. placed.

The function of the reflector is to capture the rays that do not cross the can and reflect them to the non-illuminated side.

At typical line speeds, this provides some but not complete hardening of all azimuthal strips of the can surface.

It is thus further necessary to use pairs of lamp units located at the same axial position at the height of the can, but proving mutually opposite sides of the can.

However, in this embodiment, the two lamps of each pair, such as lamp units 53 and 55 of FIG. 12, are separated from each other along the direction of can movement, each facing a reflector.

The effect of the reflector is to increase the line speed at which complete curing occurs with a given number of lamp units.

In this embodiment, a pair of 10" Fusion System ultraviolet lamp units and reflectors at a 6° angular offset are used to cure a 3" axially extending strip while moving the can at 400 feet per minute. did.

The same effect was only remotely approximated at a speed of 325 feet/minute when the lamp pair was used in normal position along the can path without a reflector.

Although the invention is illustrated with a bin chain to provide the necessary can translation, other modalities such as brush pins, conveyor belts, magnetic and vacuum conveyors, and others may be used; the essential requirement of the invention is that the cans move. It is nice to note that there is only a spatial relationship between the lamp unit and the can.

Furthermore, the present invention is not limited to curing cans;
Broadly encompasses uniform curing of three-dimensional objects.

Having described and illustrated aspects of the invention, it is to be understood that it is intended to cover all modifications thereof that are obvious to those skilled in the art and that fall within the spirit and scope of the invention. .

[Brief explanation of the drawing]

FIG. 1 shows a handmade circular reflector with a lamp bulb in the upper focus and the substrate to be cured in the lower focus. Figure 2 shows a two-piece can with the letter A printed on it. FIG. 3 is a top view of a prior art ultraviolet curing device adapted to rotate the can. FIG. 4 shows the helical cure pattern obtained by the prior art of FIG. FIG. 5 is a plan view of one specific example of the device of the present invention. FIG. 6 is a side view of the specific example shown in FIG. FIG. 7 is an end view of the embodiment of FIG. 5 illustrating the lamp unit mounting means. FIG. 8 is a diagram illustrating the geometrical aspects of a prior art curing method. FIG. 9 is a schematic diagram of the geometrical aspect of the curing method of the present invention. FIG. 10 is a schematic diagram of the light rays of the embodiment of FIG. 5 viewed from the end of the lamp unit. FIG. 11 is a schematic diagram of the light rays of the embodiment of FIG. 5, viewed from the side of the lamp unit. FIG. 12 is an illustration of yet another embodiment of the apparatus of the present invention. In the figure, 1, 14...Kan, 15, 16° 17.18, 53, 55, 57... Ultraviolet lamp unit, 12, 13, 50, 51... Bin chain, 54, 56, 58...Reflector.

Claims (1)

[Claims for Utility Model Registration] 1. A three-dimensional area of at least a single three-dimensional object having a longitudinal axis without rotation of the single three-dimensional object.
An apparatus for curing by a pair of elongated ultraviolet light source means, each elongated ultraviolet source means being located on one side of a translational path for said single article; are oriented such that their respective longitudinal directions make an angle other than 00 or 90° with the longitudinal axis, one of the light source means comprising an ultraviolet lamp unit and the other comprising reflector means. ultraviolet light source means, the length of each of said light source means being substantially greater than the length of said object in said translational path; , the front-facing surface portion of the area of the object is traversed in its entirety by a ray of light emitted isotropically from a point along the length of the elongated light source means in front of the object. means for moving the single object along the translational path in close enough proximity to the light source means to cause the object to be illuminated; The surface portion of the object substantially facing the object is hardened by the light rays emitted from the portion of the light source means between which the object is located, and the forward facing surface portion is hardened by the light beam emitted from the portion of the light source means between which the object is located. A curing device characterized in that curing is effected by said isotropically emitted light beam emitted from a point of said light source means in front of said curing device. 2. The apparatus of claim 1, wherein the longitudinal direction of each light source makes an angle of at least 78° with the longitudinal axis.