Oven for curing a powder coated product, a powder coating system and method for curing a powder coated product

Abstract

The present invention relates to a oven for curing a powder coated product, a curing system and an associated method. The oven for curing a powder coated product comprises: - a number of curing compartments for holding the products in a curing process, wherein adjacent compartments are separated by a frame having an opening, and wherein at least a part of the curing compartments are arranged relative to each other in a vertical direction; - a vertical conveyor for picking up products from and deposit products on a transfer section of the conveyor, the vertical conveyor comprising: - a number of carriers configured for carrying the products; - a number of closure elements configured for closing the opening between adjacent compartments; - a drive system configured for moving the carriers in a substantially vertical direction; and wherein the closure elements substantially close the openings in a curing step.

Description

[0001] OVEN FOR CURING A POWDER COATED PRODUCT, A POWDER COATING SYSTEM

[0002] AND METHOD FOR CURING A POWDER COATED PRODUCT

[0003] The present invention relates to an oven for curing a powder coated product. Powder coating is applied to a range of products including products like fences, bike parts, other frame parts, for example.

[0004] Curing ovens for curing powder coated products are commercially available and typically comprise a chamber or room that is heated to cure the products, whereafter the products are removed from the oven. This requires a substantial amount of product handling.

[0005] US 6 267 587 Bl, US 4 614 045 A, US 2 525 661 A, US 10228 189 Bl, US 4 738 577 A, US 2008 / 236779 Al, GB 2 345 528 A, and US 2 376 866 A disclose conventional ovens.

[0006] From practice, ovens for curing powder coated products are known that enable a continuous curing process. In such ovens the products are continuously moved along a rail, for example. The products move through the oven during the curing process. This requires a large surface area for the curing process, and further requires the use of a large amount of energy, such as heat. Therefore, such curing process involves a relatively large space in a workplace and requires substantial energy costs. Furthermore, it is known that in practice it is often difficult to maintain the desired process conditions for the curing process.

[0007] An objective of the present invention is to provide an oven for curing powder coated products that is improved relative to the prior art and wherein at least one of the above stated problems is obviated or at least reduced.

[0008] Said objective is achieved with the oven for curing a powder coated product according to the present invention, the oven comprising: a number of curing compartments for holding the products in a curing process, wherein adjacent compartments are separated by a frame having an opening, and wherein at least a part of the curing compartments are arranged relative to each other in a vertical direction; a vertical conveyor for picking up products from and deposit products on a transfer section of the conveyor, the vertical conveyor comprising: a number of carriers configured for carrying the products; a number of closure elements configured for closing the opening between adjacent compartments; a drive system configured for moving the carriers in a substantially vertical direction; and wherein the closure elements substantially close the openings in a curing step. The curing oven for powder coated products according to be present invention has a room or chamber that is divided in a number of curing compartments. Each compartment is capable of holding one, two, three, four or another suitable number of products in a curing step of the curing process.

[0009] An advantage of having different compartments in the (curing) oven according to the invention is that products can be held at desired process conditions within a compartment during a curing step of the curing process.

[0010] An advantage of the application of a vertical conveyor in the oven is that maintenance of process conditions within the compartment is improved in comparison with conventional ovens. Furthermore, the use of curing compartments reduces heat losses. More specifically, adjacent compartments may benefit from heat in the other compartments, thereby enabling a more energy efficient curing process in oven. For example, a compartment that is located above another compartment may benefit from heat that rises upwards in the lower compartment. This reduces heat losses in the upper compartment, for example. Also, a first compartment having an outside opening enabling entry of products into the (curing) oven is subjected to an additional heat loss when one or more products enter the compartment. Separating the compartments reduces the effects of such heat loss in the other compartments.

[0011] Adjacent segments are placed in a vertical configuration and enable movement of products between the compartments through an opening.

[0012] According to the invention a vertical conveyor is provided that moves the products in a substantially vertical direction, preferably up and down in the oven through the different compartments. The vertical conveyor is a continuous or semi-continuous vertical conveyor that comprises carriers that are movable in a preferably endless track, wherein said carriers are configured to transport the products between a supply and a discharge (section) of the conveyor.

[0013] The supply and discharge can be arranged at the same height level or can be arranged at different height levels. The supply provides the carrier with the product to be cured, and the processed product leaves the conveyor at the discharge for further processing.

[0014] In one of the presently preferred embodiments the carrier comprises a hanger type element, such as a hanging rod, rail, guide or other suitable element to transport products through the compartments of the oven. Products can be directly or indirectly attached to the hanger element at the supply. Optionally, products are pushed or otherwise moved over or onto the hanger element at the supply and removed in a similar manner at the discharge.

[0015] A closure element according to the present invention is configured to be able to close the aforementioned opening between two adjacent compartments. This improves control of the conditions in a compartment, and thereby improves the curing process of the powder coated product(s). In a presently preferred embodiment of the invention each carrier is provided with a closure element, wherein the closure element moves with the carrier when the vertical conveyor is in use.

[0016] By providing the carrier with a closure element the carrier can close the aforementioned opening between two adjacent compartments. Especially in a semi-continuous or batch operation this renders the curing process energy efficient. In a presently preferred embodiment, a product is maintained within a compartment during a curing step in the curing process. In this step the closure element closes the opening and thereby closes the compartment. This reduces undesired heat loss.

[0017] Furthermore, providing the carrier with a closure element provides a relatively simple configuration wherein the products are positioned correctly within a compartment and the closure elements effectively close the compartment. In fact, by providing a closure element that is movable with the carriers and products the closure of the compartment during a curing step is rendered relatively easy and effective.

[0018] In a presently preferred embodiment of the invention is the closure element provided at the upper and / or lower part of the carrier to enable closure of the respective opening between adjacent compartments in the curing step.

[0019] Providing a closure element at the top and / or bottom of the carrier such that the compartment opening is closed provides an effective means to perform (curing) operation in a compartment at desired conditions. In one of the presently preferred embodiments the closure element is provided at the bottom part of the carrier. This has as a further advantage that during loading / unloading a carrier the compartments can be effectively closed, also in case of an uneven number of compartments.

[0020] Preferably, the closure elements are provided with insulation material. This improves maintaining the desired conditions in a specific compartment.

[0021] For example, a curing step may last for 10 to 20 minutes at a temperature range of 125 to 200 °C involving different curing steps. Energy can be supplied from an energy source by convection and / or other ways that may involve heat, infrared or other suitable energy source. Such energy source is also referred to as heater in the context of the present invention.

[0022] A further advantage of the application of a vertical conveyor in an oven for curing a power coated product according to the present invention is its suitability for autonomous or semi- autonomous operation, optionally involving the application of one or more AGV’s. This replaces or prevents conventional rails or guide tracks, thereby improving the flexibility of the overall system.

[0023] As an even further effect the operation can be performed more easily at any appropriate moment. For example, when using solar energy, the powder coating process can be performed when sufficient (solar) energy is available. This improves the overall energy efficiency and reduces the overall carbon footprint of the end-product. In a presently preferred embodiment of the invention the number of compartments is at least three, and more preferably four. It will be understood that any other number of compartments can be applied depending on the curing process and product.

[0024] In a presently preferred embodiment of the invention at least some of the compartments extend over a lifting part of the vertical conveyor and a lowering part of the vertical conveyor.

[0025] By extending compartments over both a lifting part and a lowering part of the vertical conveyor heat can be exchanged between products from a lowering part to the lifting part. This provides an energy efficient heating process and curing step. Optionally, compartments are stacked vertically and extend horizontally over the lifting and lowering parts of the vertical conveyor. Alternatively, the lifting and lowering parts of the vertical conveyor are provided with separate compartments.

[0026] In a further preferred embodiment of the invention the oven for curing a powder coated product comprises a gas outlet.

[0027] By providing a gas outlet the heated gas in the compartment that is used for the curing process can be transferred to a further process. Especially the provision of a gas outlet in the upper compartment of the oven improves the overall energy efficiency. The energy can be provided to a drying operation in the same manufacturing process, for example.

[0028] Preferably, heat is exchanged between the medium / air from the oven and the medium / air that is used in the drying operation. Optionally, use is made of a heat exchanger to prevent a direct exchange of medium / air between different processes. Alternatively, the energy can be used in other processes, such as another manufacturing operation or heating of a building, for example by underfloor heating.

[0029] In a further presently preferred embodiment of the oven according to the invention a ventilating device is provided. Such ventilating device enables application of forced convection to improve the curing process. The ventilating device may relate to a ventilator or nozzle or other suitable device.

[0030] In a further presently preferred embodiment of the oven according to the invention the oven further comprises a controller configured for controlling the conditions in compartments of the oven. Such controller preferably maintains the desired conditions, such as temperature, in the individual compartments. These temperatures can be the same or different, depending on the desired curing process for the products. Preferably, the controller also controls the residence time(s) for the products in a compartment. The controller is preferably operatively connected to a number of sensors inside and / or outside the compartment(s) and preferably also to the energy sources that are provided in the compartment(s). The controller may have any suitable configurations, including a central configuration with a central controller or decentral configuration with (only) co-operating local controllers. The invention further relates to a curing system comprising an oven for curing a powder coated product according to an embodiment of the present invention, and a dryer.

[0031] Such curing system provides the same or similar effects and advantages as described in relation to the oven for curing a powder coated product.

[0032] In a presently preferred embodiment of the powder coating system a gas outlet of the oven is operatively connected to the dryer to thereby improve the overall energy efficiency. Preferably, heat is exchanged between the medium / air from the oven and the medium / air that is used in the drying operation. Optionally, use is made of a heat exchanger.

[0033] The invention further also relates to a method for curing powder coating products, with the method comprising the steps of: providing an oven for curing the powder coated products in an embodiment according to the present invention; and curing the product.

[0034] Such method provides the same or similar effects and advantages as described in relation to the oven for curing a powder coated product and / or powder coating system. In a presently preferred embodiment of the invention the method further comprises the step of providing each carrier with a closure element that moves with the carrier. This provides an effective method for efficiently curing the powder coated products.

[0035] Optionally, gas is provided from the oven to other equipment, such as a dryer, using a gas outlet. Heat from the medium / air is preferably transferred to the medium / air that is used in the drying operation with a heat exchanger.

[0036] Optionally, a buffering step is used for buffering products before entry into the powder coating oven. This enables performing the curing process at an optimal moment in time. This can be achieved by performing the curing process when wind and / or solar energy is available. This optimizes the overall sustainability of the curing process. The buffer that enables buffering the products before entry into the oven for curing a powder coated product enables such optimization.

[0037] The various aspects and features described and shown in the specification can be applied, individually, wherever possible. These individual aspects, and the particular aspects and features described in the attached depended claims, may be made subject of divisional patent applications.

[0038] Further advantages, features and details of the invention are elucidated on the basis of preferred embodiments thereof, wherein reference is made to the accompanying drawings, in which:

[0039] Figure 1 shows an oven for curing a powder coated product according to the invention;

[0040] Figures 2 A-C show different views of the vertical conveyor of the oven of figure 1 ;

[0041] Figure 3 shows an operation of the oven of figure 1 ;

[0042] Figures 4 A-B show alternative configurations for the oven of figure 1 ; Figures 5A-C show alternative carriers for an oven according to the invention;

[0043] Figure 6 shows an alternative carrier for oven according to the invention with the carrier having a closure element at the bottom

[0044] Figure 7 shows the manufacturing process with the curing process in the oven of figure 1.

[0045] Oven 2 (figure 1) for curing a powder coated product comprises housing 4 with vertical conveyor 6. In the illustrated embodiment vertical conveyor 6 comprises first conveyor part / unit 6a and second conveyor part / unit 6b. Such vertical conveyor 6 with conveyor parts / units 6a, b can be placed in (curing) oven 2. Such conveyor 6 may involve an operational system similar to the so- called twin MK 5 conveyor lift that is developed and offered by the applicant.

[0046] The vertical conveyor 6 comprises endless track 8 that provides a number of carriers 10. Each carrier comprises hanger element 12 and closure element 14. As is schematically indicated, closure elements 14 can be provided with insulation layer 15, for example at the top or bottom surfaces. In addition or as an alternative, closure element 14 can be made of an insulation material and / or comprise a layer of insulation material.

[0047] Oven 2 for curing a powder coated product is provided with separate compartments, including upper compartment 16, a number of intermediate compartment 18, and supply and / or discharge compartment 20a, b. In the illustrated embodiment supply and / or discharge compartments 20a, b are provided at the same height. It will be understood that other configurations with compartments 20a, b at different heights can also be envisaged in accordance with the present invention. Adjacent compartments are separated by opening 22 in frame 24 with insulating elements or insulating layers 26.

[0048] Schematically illustrated are one or more controllers 28 that are operatively connected to a number of sensors 30, and to one or more energy sources / heaters 32 for providing energy to the curing process. In the illustrated embodiment controllers 28, sensors 30, and energy sources / heaters 32 are provided in every compartment. Optionally, supervisor controller 28a is provided outside the compartments for controlling oven 2 in co-operation with controllers 28, sensors 30 and further information, including ambient sensors 30a and logistic information 30b. It will be understood that other control configurations can also be applied in accordance with the present invention, such as an integrated (local) controller 28 that is integrated with the supervisor controller 28a or supervisor controller 28a directly controlling individual compartments. It will also be understood that energy can be supplied from energy source / heater 32 by convection and / or other ways that may involve heat, infrared or other suitable means.

[0049] Optionally, ventilating device 34 and / or gas outlet 36 are provided in one or more of compartments 16,18,20.

[0050] Elevator 4 is capable of moving products in direction A (figure 2A) having a lifting part 38 and a lowering part 40. In the illustrated embodiments there is provided upper segment 16, intermediate segments 18a-c and supply and / or discharge compartment 20. Products 42 (figure 2B) hang on one of the hanger elements 12 that are provided below closure element 14 of carrier 10. closure elements 14 fit in opening 22 that is defined by frame 24, and, when in position, substantially close opening 22.

[0051] In supply and / or discharge section 20 and upper compartment 16 carrier 10 is maintained in its carrying position, preferably in a similar manner as developed and offered by the applicant in the aforementioned conveying device. Products can be hung or pushed onto hanger element 12.

[0052] In alternative configuration 52 (figure 3) four compartments are provided in housing 4 of oven 2 for curing a powder coated product. The compartments comprise upper segment 16, intermediate compartment 18a,b, and supply and / or discharge compartment 20. In this configuration compartments 16, 18a, b, 20 extend vertically over a certain height, and horizontally include both lifting part 38 and lowering part 40 of conveyor 2 to enable energy exchange between the two parts. In this illustrated configuration 52 there are always two carriers within each compartment.

[0053] It will be understood that other configurations can also be envisaged in accordance with the present invention. For example, configuration 62 (figure 4 A) comprises upper segment 16, intermediate compartments 18a, b and supply and / or discharge compartment 20. In this configuration 62, upper compartment 16 has three positions for products 42, and supply and / or discharge compartment 20 has one position for product 42. Therefore, products 42 are maintained for a longer time period at a higher temperature in upper compartment 16. This configuration 62 can advantageously be used for supply and discharge of products 42 in a direction transversal to the illustrated view. This configuration as illustrated has an uneven number of carriers and in this illustrated embodiment providing closure elements 14 at the bottom of carrier 10 can be applied advantageously.

[0054] Alternative configuration 72 (figure 4B) comprises upper segment 16 with four product positions, one intermediate section 18 and a supply and / or discharge compartment 20. It will be understood that further alternative embodiments according to the present invention can also be envisaged.

[0055] In an alternative embodiment, carrier 10 (figure 5A-C) comprises a toothed or serrated hanger element 12a. Serrated hanger element 12a is connected through (moveable) connectors 12b to rod 12e and with hangers 12d to carrier 10 (figure 5A), or is directly connected to carrier 10 with hangers 12b (figure 5B). Product 41 is connected with hooks 12c to alternative hanger element 12a. Serrated hanger element 12a (figure 5C) is connected to trolley 13 and profile 11 in connection with door 14 and trolley shaft 9. It will be understood that such configuration with serrated hanger element 12a can also be applied in combination with other features of oven 2 as are illustrated in other figures, for example. Furthermore, it will be understood that further alternative configurations can also be envisaged in accordance with the present invention. Alternative carrier 202 (figure 6) comprises hanger element 204 and closure element 206 that is optionally provided with insulation layer 208. Frame 210 connects closure element 206 at the bottom of carrier 202 with the top part of carrier 202 with hanger element 204. In the illustrated embodiment (optional) gauze or mesh element 212 is provided as sidewalls of carrier 202. Connecting mechanism 214 connects carrier 202 to the other parts of conveyor 6 and enable movement of carrier 202, when in operation.

[0056] Manufacturing process 82 (figure 7) starts with supply 84 of product materials whereafter a product is manufactured in production step 86. In manufacturing process 82 products are washed in washing step 88, dried in drying step 90, coated in coating step 92, and optionally buffered in buffering step 94 before being cured in curing step 96. Curing step 96 uses oven 2. Products are then provided to other processing steps in further processing step 98 that may involve storage, transport, display et cetera. Optionally, energy from a wind and / or solar source is generated in energy step 100 and provided to oven 96. Furthermore, optionally in energy saving step 102, energy is transferred from curing step 96 to drying step 90.

[0057] In curing step 96 products 42 are provided to carriers 10, 202 in supply compartment 20. Carriers 10, 202 move to the next compartment such that closure element 14 closes opening 22 in frame 24 of oven 2. Products 42 are maintained in the compartment for a specific time period and at specific conditions. Then, carriers 10, 202 are moved to the next compartment for the next curing step. For example, a curing step may last for 10 to 20 minutes at a temperature range of 125 to 200 °C involving different curing steps. Products 42 that arrive in discharge section 20 are removed from carrier 10, 202 for further handling and / or processing.

[0058] The present invention is by no means limited to the above-described preferred embodiments thereof. The rights sought are defined by the following claims within the scope of which many modifications can be envisaged. For example, insulation 15, 208 can be applied to all embodiments of carriers 10, 202. This also applies to sidewalls 212 and other elements.

Claims

CLAIMS1. Oven for curing a powder coated product, the oven comprising: a number of curing compartments for holding the products in a curing process, wherein adjacent compartments are separated by a frame having an opening, and wherein at least a part of the curing compartments are arranged relative to each other in a vertical direction; a vertical conveyor for picking up products from and deposit products on a transfer section of the conveyor, the vertical conveyor comprising: a number of carriers configured for carrying the products; a number of closure elements configured for closing the opening between adjacent compartments; a drive system configured for moving the carriers in a substantially vertical direction through compartments; and wherein each carrier is provided with a closure element, and wherein the closure elements are configured for substantially closing the openings in a curing step.

2. Oven according to claim 1, wherein the closure element is configured for moving with the carrier when the vertical conveyor is in use.

3. Oven according to claim 2, wherein the closure element is provided at the upper and / or lower part of the carrier to enable closure of the respective opening between adjacent compartments in the curing step.

4. Oven according to claim 1, 2 or 3, wherein the closure elements are provided with insulation material.

5. Oven according to any of the foregoing claims, wherein the number of compartments is at least 3, and preferably 4.

6. Oven according to any of the foregoing claims, wherein at least some of the compartments extend over a lifting part of the vertical conveyor and a lowering part of the vertical conveyor.

7. Oven according to any of the foregoing claims, wherein the number of carriers is provided in an endless track.

8. Oven according to any of the foregoing claims, wherein the carrier comprises a hanger element.

9. Oven according to any of the foregoing claims, further comprising a gas outlet.

10. Oven according to the foregoing claim, wherein the gas outlet is provided in the upper compartment.

11. Oven according to any of the foregoing claims, further comprising a ventilating device.

12. Oven according to any of the foregoing claims, further comprising a controller configured for controlling the conditions in compartments of the oven.

13. Curing system comprising an oven for curing a powder coated product according to any of the foregoing claims, and a dryer.

14. System according to the foregoing claim, wherein a gas outlet of the oven for curing a powder coated product is operatively connected to the dryer.

15. Method for curing powder coated products comprising the steps of: providing an oven for curing a powder coated product according to any of foregoing claims 1-12; and curing the products.

16. Method according to the foregoing claim, further comprising the step of providing each carrier with a closure element that moves with the carrier.

17. Method according to claim 15 or 16, further comprises a step of buffering products in a buffer before entry into the oven.

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