EP2653814A1

EP2653814A1 - Method and apparatus for drying paint applied on mainly flat parts

Info

Publication number: EP2653814A1
Application number: EP13163587.2A
Authority: EP
Inventors: Stefano Benedetti; Silver Santandrea
Original assignee: Cefla SCARL
Current assignee: Cefla SCARL
Priority date: 2012-04-16
Filing date: 2013-04-12
Publication date: 2013-10-23
Anticipated expiration: 2033-04-12
Also published as: CN103372529A; PL2653814T3; ITBO20120203A1; EP2653814B1; ES2575926T3; CN103372529B

Abstract

Apparatus (11) for drying paint applied on the surface and vertical edges of basically flat parts (14), comprising a UV lamp (12), a reflector (13) and a conveying system (15, 16, 17) for translating the flat part beneath the reflector (13), wherein
it comprises only one reflector (13) having elliptical shape, positioned so that ellipse's major axis crossing both foci is perpendicular to the part to be dried (14), wherein the UV lamp (12) is in the first focus of the ellipse and wherein the second focus is in proximity of the lower edge of reflector (13).

Description

The present invention refers to the technical field of apparatuses for drying paint applied on mainly flat parts through the use of UV rays. In particular, the invention relates to a suitably shaped reflector which allows to concentrate UV radiations emitted by a UV lamp, so as to accelerate the drying of paint applied on said articles.
According to the prior art, a tubular lamp is used which emits UV radiations which are reflected through a suitably shaped parabolic or elliptic reflector on the horizontal surface and vertical edges of the panel to be dried. In the case of a parabola, the lamp is positioned in its focus. In the case of an ellipse, the lamp is positioned in one of the two foci of the ellipse, which is sectioned in its portion directed toward the part to be dried. In the prior art, reflectors having both shapes are already in use, in order to obtain a diffused or concentrated irradiation on the parts to be dried.
From US 5300331 A an apparatus for drying paint applied on the surface and vertical edges of flat parts is known comprising two identical reflectors having elliptical shape, positioned so that ellipse's major axis crossing both foci is perpendicular to the part to be dried, wherein the UV lamp is in the focus of the ellipse and wherein the second focus is in proximity of the lower edge of the article.
In the drying of paint applied both to the flat top and to the vertical edges of an article, typically two reflectors must be used, which must be suitably tilted towards the leading and trailing edges of the part, so as to dry said vertical edges.
One of the advantages of the present invention lies in the possibility of using just one reflector which allows to suitably dry the edges, which are parallel and perpendicular to part feed direction; this allows to build simplified, less costly drying ovens. The oven making use of UV lamps is in fact very expensive; moreover the use of just one lamp allows to spare energy and heat less the part to be dried.
The present invention will now be described in one of its embodiments with the help of the following figures, showing:

Figure 1: a lateral view of a prior art oven, making use of two modules, each comprising a lamp and a reflector;
Figure 2: a lateral view of the present invention on the whole;
Figure 3: a detail of the rays reflected by reflector;
Figure 4: a frontal view of the present invention on the whole.

In Figure 1, 1 denotes on the whole a prior art apparatus for drying the paint applied on parts, represented in a lateral view. 2a and 2b denote two UV lamps, here represented in a lateral section; 3a and 3b are the elliptic reflectors surrounding the lamps; 4 the painted part, moving in the direction shown by the arrow. 5 is the conveyor, 6 the bars supporting and conveying parts 4, 7 the pinions which move bars 6 forward through chains (not shown). In this kind of prior art apparatus two lamps 2a, 2b must be employed, contained in two reflectors 3a, 3b, which must be suitably tilted with respect to part 4. For better clarity, in reflector 3a only non-reflected UV rays 9 emitted by the lamp, while in reflector 3b only reflected rays 8, concentrated on part 4, are represented. It is apparent that in reality each lamp 2a, 2b emits both non-reflected rays 9 and reflected rays 8. It is equally apparent that, with this configuration, an important share of non-reflected rays 9 does not participate in paint drying. This share of non-reflected rays 9, which would be wasted, is usually recovered with the help of additional reflectors, which increase the complexity and the costs of the apparatus.
In Figure 2 a lateral view of an apparatus 11 according to the present invention is represented, which makes use of just one UV lamp 12 and of just one reflector 13. The lamp 12 is in the first focus of the elliptic reflector 13. Reflector 13 is perpendicular to part 14 to be dried, i.e. the major axis of the ellipse, crossing both foci, forms an angle of 90° with the major axis of part 14. Reflected rays 18 are concentrated on part 14 horizontal surface, while non-reflected rays 19 hit directly the top surface of part 14, which moves according to arrow direction. Conveying system 15, 16, 17 is the same as in Figure 1.
In Figure 3 a detail of UV path is represented, which highlights how reflected UV rays 18 can surprisingly hit also the vertical leading and trailing edges 22, 22' of advancing part 14, ensuring a satisfactory drying of the edges 22, 22'. For better clarity, only half of reflected rays 18, relative to half of the reflector, are shown in the Figure.
In the same Figure 3, it can be appreciated that the second focus 21 of the elliptical reflector must be just under the edges of the reflector itself.
Figure 4 represents the apparatus of the present invention in a frontal view, perpendicularly to feed direction. Mirrors 23 are present, which are perpendicular to the axis of the lamp 12, which allow to reflect the share of rays, which would hit the wall, on lateral edges 20. In this Figure the fact that reflected UV rays 18 and non-reflected UV rays 19 can hit vertical lateral edges 20, parallel to feed direction, of part 14 can be appreciated.
In order to optimally exploit UV rays emitted by lamp 12, it is apparent that fixed mathematical ratios between the position of lamp 12 coinciding with the first focus of the ellipse, the position of the second focus 21 and edge thickness 20 must be respected. The position of focus 21 is fixed and is a function of the shape of the elliptical reflector 13.
Lamp 12 is in a fixed position within reflector 13, the two components are integral: the movement of reflector 13 entails the shift of lamp 12 with respect to part 14 to be dried.
The thickness of edge 20 of part 14 can vary in a range of some millimetres to some centimetres, and the position of focus 21 with respect to conveyor 15 must be varied consequently, suitably positioning both lamp 12 and reflector 13. The positioning of lamp 12 and reflector 13 as a whole can be performed in known ways, as a motor or a jack. It is up to operator, at the beginning of operation, to adjust the apparatus according to part thickness.

1: Prior art apparatus as a whole
2: UV lamp
3: Reflector
4: Part
5: Conveyor
6: Conveyor bars
7: Conveyor pinions
8: Reflected UV rays
9: Non-reflected UV rays
11: Present invention oven
12: UV lamp
13: Reflector
14: Part
15: Conveyor
16: Bars
17: pinion
18: reflected UV rays
19: non-reflected UV rays
20: part lateral edges
21: second focus
22 ;22': leading and trailing vertical edges of the part
23: lateral mirrors

Claims

Apparatus (11) for drying paint applied on the surface and vertical edges of basically flat parts (14), comprising a conveying system (15, 16, 17) a UV lamp (12), a reflector (13),
characterized in that
it comprises only one reflector (13) having elliptical shape, positioned so that ellipse's major axis crossing both foci is perpendicular to part (14) to be dried, wherein UV lamp (12) is in the first focus of the ellipse and wherein the second focus is in proximity of the inferior edge of reflector (13).
Apparatus according to claim 1, wherein lamp (12) is fixed within reflector (13), and reflector (13) and lamp (12) are integrally movable in a vertical direction with respect to part (14) to be dried.
Apparatus according to claim 2, wherein the position of lamp (12) and reflector (13) is adjusted according to the thickness of part (14) to be dried.
Apparatus according to any of the preceding claims, wherein reflected rays (18) hit leading and trailing vertical edges (22; 22') of the part (14) to be dried.
Apparatus according to any of the preceding claims, wherein lateral edges 20 of the part (14) to be dried are hit by direct rays (19) and indirect rays (18) reflected by mirrors (23) positioned laterally with respect to reflector (13) and perpendicular to lamp (12) axis.
Apparatus according to any of the preceding claims 1, wherein UV lamp (12) can be tubular or punctiform.
Method for drying paint applied on the upper surface and on the vertical leading and trailing edges (22; 22') as well as on the lateral edges (20) of a mainly flat part(14), comprising the steps of:
- irradiating said article by means of a single elliptical reflector (13) having an UV lamp (12) positioned in its first focus, the second focus (21) being positioned in proximity of the lower edge of the reflector (13), and in which the ellipse's major axis passing through the two foci of the reflector (13) is perpendicular to the surface of the part (14) to be dried;

- and translating said part beneath said reflector (13) so that the rays (18) reflected by the reflector (13) hit first the leading edge (22), thereafter the upper surface and the lateral edges (20) and finally the trailing (22') edge of the part (14).