Vertical oven for mainly flat parts

Abstract

A vertical oven for panels includes trays configured to support mainly flat panels arranged in a multiple of two stacks circulating in opposed directions, such as the first stack moving in an ascending direction and the second stack in a descending direction. The trays are arranged at a distance from each other and the movement of the trays is such that at least one every other tray is withdrawn from the circulation, doubling the distance between the trays.

Claims

1. A vertical oven for drying painted objects, the oven comprising: at least two vertical transit chambers (21, 22); a plurality of trays (41, 42, 43, 44, 45, 46, . . . ) configured to support the painted objects, the plurality of trays being arranged in a stack (31, 32; 81, 82, 83, 84) of superimposed trays within each of the at least two transit chambers (21, 22); and motorized tray conveyors that displace the trays along a path comprising at least an ascending portion inside a first transit chamber of the at least two transit chambers, a lateral shifting portion from the first transit chamber to a second transit chamber of the at least two transit chambers, and a descending portion inside the second transit chamber, wherein one or both of an input or output port are provided at a bottom of the at least two transit chambers, at which there is provided alternatively or in combination a loading unit, an unloading unit of the dried painted objects from the trays, and a conveyor shifting the trays from a lower end of the second transit chamber to a lower end of the first transit chamber for recirculating the trays along the path inside the at least two transit chambers, wherein the trays (41, 42, 43, 44, 45, 46, . . . ) have a predefined distance from each other in the stacks inside the at least two chambers (21, 22), wherein the vertical oven includes at least one parking chamber (23); wherein the at least one parking chamber (23) is configured to temporarily park one or more of the trays (42, 44, 43) in a stack of parked superimposed trays; wherein transferring devices adapted to withdraw trays from the stack of the first or the second transit chamber and feed the trays to the at least one parking chamber or for re-insertion of the trays in the stack of said first or said second transit chamber, and wherein a control unit controls the transferring devices to withdraw every second tray in the stack of the first or the second transit chamber and parks the withdrawn tray in the at least one parking chamber (23), thus doubling the predefined distance between the trays in the stack of the first or the second transit chamber (31, 32; 81, 82, 83, 84).

2. The vertical oven according to claim 1, wherein the at least one parking chamber (23) is positioned between the at least two transit chambers (21, 22).

3. The vertical oven according to claim 1, wherein the at least one parking chamber (75, 76) is arranged at one side of the path or of one of the at least two transit chambers (71, 72, 73, 74).

4. The vertical oven according to claim 1, wherein the vertical oven has only two transit chambers.

5. The vertical oven according to claim 1, wherein the at least two transit chambers are two or more pairs of transit chambers.

6. The vertical oven according to claim 1, wherein the oven is provided with two parking chambers (75, 76).

7. The vertical oven according to claim 1, wherein the at least one parking chamber (23, 75, 76) is provided with a heater.

8. The vertical oven (51, 61) for panels according to claim 1, wherein the trays (41, 43, 45, . . . ) having double the predefined distance from each other due to withdrawals of every second tray support panels having a higher thickness than other panels.

9. The vertical oven (51) according to claim 1, wherein the control unit is configured to set different dwelling times for the trays in the parking chamber.

10. A method of drying mainly flat painted panels comprising: providing a vertical oven comprising: at least two vertical transit chambers (21, 22); a plurality of trays (41, 42, 43, 44, 45, 46, . . . ) configured to support the painted objects, the plurality of trays being arranged in a stack (31, 32; 81, 82, 83, 84) of superimposed trays within each of the at least two transit chambers (21, 22); and motorized tray conveyors that displace the trays along a path comprising at least an ascending portion inside a first transit chamber of the at least two transit chambers, a lateral shifting portion from the first transit chamber to a second transit chamber of the at least two transit chambers, and a descending portion inside the second transit chamber, wherein one or both of an input or output port are provided at a bottom of the at least two transit chambers, at which there is provided alternatively or in combination a loading unit, an unloading unit of the dried painted objects from the trays, and a conveyor shifting the trays from a lower end of the second transit chamber to a lower end of the first transit chamber for recirculating the trays along the path inside the at least two transit chambers, wherein the trays (41, 42, 43, 44, 45, 46, . . . ) have a predefined distance from each other in the stacks inside the at least two chambers (21, 22), wherein the vertical oven includes a parking chamber (23); wherein the parking chamber (23) is configured to temporarily park one or more of the trays (42, 44, 43) in a stack of parked superimposed trays; wherein transferring devices adapted to withdraw trays from the stack of the first or the second transit chamber and feed the trays to the parking chamber or for re-insertion of the trays in the stack of the first or the second transit chamber, wherein a control unit controls the transferring devices to withdraw every second tray in the stack of the first or the second transit chamber and parks the withdrawn tray in the parking chamber (23), thus doubling the predefined distance between the trays in the stack of the first or the second transit chamber (31, 32; 81, 82, 83, 84), wherein even trays (42, 44, 46, . . . ) in the stack follow a different path from a path of odd trays (41, 43, 45, . . . ) in the stack, and wherein the even trays (42, 44, 46, . . . ) are parked in a pre-set area (22; 75, 76) for any desired time, and wherein the odd trays are driven along a predefined path and with an increased distance between the odd trays (41, 43, 45, . . . ), the increased distance corresponding to a double distance of the stack before transferring the even trays into the parking chamber adjacent to the first and the second transit chamber.

11. The method according to claim 10, wherein the even trays (42, 44, 46, . . . ) in the parking chamber (22; 75, 76) support or do not support the panels.

12. The method according to claim 11, wherein if the even trays (42, 44, 46, . . . ) support the panels, the parking chamber (22, 75, 76) is heated.

13. The method according to claim 10, wherein a dwell time of the even trays (42, 44, 46, . . . ) in the parking chamber (22; 75, 76) is inputted by an operator when loading an oven containing the first and the second transit chamber, or is decided when reinsertion of the even trays (42, 44, 46, . . . ) is necessary.

Description

(1) Further advantages and properties of the present invention are disclosed in the following description, in which exemplary embodiments of the present invention are explained in detail on the basis of the drawings:

(2) FIG. 1 Typical painting production line, in a top view;

(3) FIG. 2 Oven with three chambers and two stacks according to the known art;

(4) FIG. 3 First embodiment: oven having three chambers and two stacks;

(5) FIG. 4 Second embodiment: oven having four/six chambers with external parking area.

(6) The shown embodiments are meant as examples of the different and various possibilities of plant configuration, and in particular of the oven according to the present invention, as well as of its possible multiple operating modes. The embodiments illustrated and discussed in this specification are intended only to teach those skilled in the art the best way known to the inventors to make and use the invention. Nothing in this specification should be considered as limiting the scope of the present invention. Modifications and variations of the above-described embodiments of the invention are possible without departing from the invention, as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the claims and their equivalents, the invention may be practiced otherwise than as specifically described, the configuration being determined by the requirements of treatment of the products to be dried and of their shape and dimension features.

(7) Different features provided in combination with a specific embodiment may be provided also in combination with other embodiments. This particularly relates to the number and relative position of the transit chambers and of the parking chambers of the different embodiments shown in the figures. As it will appear from the following description, the lateral position of the one or more parking chambers may apply to the embodiment having only two transit chambers as well as the intermediate positioning of at least one parking chamber between two transit chamber may apply also to the embodiment showing four of more than four transit chambers.

(8) When more than one parking chamber is provided, also a combination of the said lateral and intermediate positioning of one parking chamber may be applied to both the embodiments with only two and with more than two transit chambers.

(9) FIG. 1 shows a typical painting production line 1 comprising a typical vertical oven 1. Typically, the (not shown) panel, loaded on a conveying system 11, is painted in a spraying booth 12 and from that point conveyed through a conveying system 13 to an oven 1 for drying. The panel is automatically loaded on a tray of the oven 1, lifted, horizontally shifted, and then lowered to be finally unloaded from the same loading side 14, to be conveyed to the painting booth again.

(10) FIG. 2 shows a typical oven 1, wherein three transit chambers 21, 22, 23 and two stacks 31, 32 according to the known art are formed inside respectively two of the said three chambers which are indicated as transit chambers 21, 23. Each stack 31, 32 is provided with a plurality of trays 41, 42, 43, 44, 45, 46, . . . for loading panels, arranged in two stacks 31, 32. When a tray 41 reaches the top of the ascending chamber 23, it is shifted on the top of the descending chamber 21 through suitable horizontal shifting devices, for example as the one disclosed above in relation to the prior art documents. With similar devices, at the end of the last descending chamber, the trays are shifted to the base of the first ascending chamber 23 to be taken from the relative lifting chain. In this way, every tray of the oven follows a complete path through the entire oven, as shown with the arrows, during which the panels arranged on trays dry. As can be clearly observed from FIG. 2, the central chamber 22 is empty.

(11) The path of the trays is normally closed while the dried objects may be loaded and unloaded at an input and at an output port of the said transit chambers, preferably at the bottom end of the said transit chambers.

(12) FIG. 3 shows an oven 51 having three chambers 21, 22, 23 and two stacks 31, 32 according to the present invention. The oven 51 is substantially equal to the oven 1 of the known art, with the difference that the panels in oven 51 can perform two different paths: a first path equal to the known art; a second path wherein odd trays 41, 43, 45 . . . follow the path of the known art along stacks 31, 32, while even trays 42, 44, 46, . . . , when charged with the (not shown) panels to be dried, are stored in the central parking chamber 22. Alternatively, empty even trays 42, 44, 46, . . . are parked in the central parking chamber 22.

(13) This allows to double the distance between an odd tray 41 and its consecutive tray 43 (from d to 2d), which in turn allows to load the trays with panels having a thickness up to 200 mm, or anyway thicker than the standard thickness.

(14) Moreover, this also allows to use the same oven 51 for two distinct drying processes at the same time, each having a different drying time: The panels loaded on odd trays 41, 43, 45, . . . have a drying time equal to the panels following the normal path, which is substantially linked to oven's design parameters (a fixed time determined by chain features, distance between trays, conveying system, production line speed); The panels loaded on even trays 42, 44, 46, . . . have drying times which can be freely chosen, in the sense that they can dwell in the central parking chamber 22 until the operator decides to re-insert them in the normal path and allow their unloading according to normal modalities.

(15) In this way, the oven 51 according to the present invention allows to perform the drying of panels having different drying requirements, and moreover to dry panels having a thickness higher than standard, which normally cannot dry in an oven, the oven footprint being equal with respect to known art ovens.

(16) On the other hand, FIG. 4 shows a second embodiment of the present invention, i.e. an oven 61 having four transit chambers 71, 72, 73, 74 and four stacks 81, 82, 83, 84, per se already known in the art. The invention adds to the oven a side couple of parking chambers 75, 76, wherein even trays 42, 44, 46, . . . are temporarily parked, while odd trays continue in their typical meandering path, as shown by the arrows.

(17) In this embodiment, too, odds trays are spaced of a double distance 2d with respect to the habitual arrangement of trays. Therefore odd trays can host panels having a thickness higher than standard, continuing their meandering path with the standard time of oven 61. On the other hand, even trays 42, 44, 46, . . . can dwell in the two parking chambers 75, 76 for any desired time before being re-inserted in the normal path of trays to be unloaded after a desired time.

(18) The two parking chambers 75 and 76 can, or cannot, be heated being provided or not with heating means.

(19) In the embodiment wherein the two parking chambers 75 and 76 are heated, the working of the oven doubles as explained in paragraph 0031, and therefore in the same oven 61 panels having distinct drying time are loaded at the same time.

(20) In the embodiment wherein the parking chambers 75 and 76 are not heated, they become simply a sort of parking area for even trays 42, 44, 46, . . . , which have to be removed from the normal meandering path in order to allow the loading of panels thicker than standard on odd trays 41, 43, 45, . . . following the normal meandering path with its characteristic time.

(21) Concerning the conveying of trays, and the possibility of sending even trays in the parking area, the design of mechanical solution allowing to send the trays to two different directions is part of the known art for the skilled person, and therefore will not be discussed in detail.

(22) When even trays are sent to parking area 22; 75, 76, different working possibilities are provided.

(23) If the trays are loaded with panels, when loading a human operator, through man-machine interface, will have to possibility to input a dwell time inside the parking area that, as already explained, is independent from the cycle time characteristic of the oven. E.g. if the cycle time of the oven is one hour, the dwell time in the parking area could be two, three, . . . twenty-four hours according to operator's choice.

(24) If the trays are unloaded, a human operator can deviate even trays to the parking area, which dwell there until they are manually called back in the cycle by the human operator. 1 three chambers, two stack oven according to known art 10 typical painting production line 11 loading device 12 spraying booth 13 conveyor to the oven 14 back conveyor to spraying booth 21, 22, 23 three chambers 31, 32 two stacks 41, 43, 45, . . . odd trays 42, 44, 46, . . . even trays 51 three chambers, two stack oven according to the present invention 61 four chambers, four stack oven according to the present invention 71, 72, 73, 74 chambers 81, 82, 83, 84 stacks