DEVICE FOR CHEMICAL TREATMENT OF A SURFACE

Abstract: The invention relates to a device for treating a surface of an object with a treatment liquid, which device comprises: a rotatable frame; a liquid container arranged in the frame and having an opening which substantially corresponds in dimensions with the surface for treatment; and clamping means for clamping the object on the opening of the liquid container such that the surface for treatment is directed toward the container and closes the opening.

Description: DEVICE FOR CHEMICAL TREATMENT OF A SURFACE The invention relates to a device for treating a surface of an object with a treatment liquid. It is known to treat metal surfaces with treatment liquids. A surface can thus for instance be cleaned, hardened, nitrated or galvanized. A great drawback of the treatment liquids is that they are often harmful to health and the environment and can cause injuries in contact with the skin. In order to treat a surface the object is usually immersed in a bath. The drawback hereof is that the whole object comes into contact with the liquid, whereby surfaces of the object are also treated which do not necessarily require treatment. In addition, baths are required in which the object can be at least partly immersed. Furthermore, a part of the liquid will evaporate through heating, whereby the concentration changes and it is difficult to ensure a correct quality of the treatment . It is an object of the invention to prevent the above stated drawbacks. This object is achieved according to the invention by a device which comprises: - a rotatable frame; - a liquid container arranged in the frame and having an opening which substantially corresponds in dimensions with the surface for treatment; and - clamping means for clamping the object on the opening of the liquid container such that the surface for treatment is directed toward the container and closes the opening. Because the object is arranged on the opening of the liquid container, the content of the liquid container can be limited to a volume such that the liquid can only just wet the surface. Since the whole of liquid container and object encloses the liquid, the danger of direct contact with the liquid or indirectly by means of vapour is considerably reduced. In a preferred embodiment of the device according to the invention heating means are arranged on the liquid container. For some treatments it is necessary for the liquid to have a certain temperature. The liquid is held at the desired temperature by the heating means. In a preferred embodiment for treating the surface such that a spectrally selective surface results, the heating means hold the liquid at about 70°C. For such a treatment the treatment liquid comprises chromic acid and/or sulphuric acid. Known spectrally selective layers consist of a thick coating of complicated composition. A drawback of such known layers is that they are thermally insulating. The temperature of the layer can hereby rise very high during use. Owing to this high temperature problems can occur in respect of adhesion to the substrate, and the lifespan can moreover be limited hereby. By providing a spectrally selective surface with a liquid, no adhesion problems and the like will occur. In another embodiment a device according to the invention comprises control means for controlling the treatment process, which control means are galvanically connected to both the surface for treatment and the liquid. The progress of the treatment of the surface can be measured by measuring the potential between the liquid and the surface. By having control means measure this potential the treatment process can be automated and surfaces of a desired quality can be obtained. In another embodiment of the device according to the invention the control means apply a galvanic potential between the liquid and the surface for treatment . The chemical treatment can be accelerated, decelerated or even stopped by applying a galvanic potential . In yet another preferred embodiment of a device according to the invention a plate is arranged in the opening of the container such that a passage opening is kept clear between at least one side of the opening and one side of the plate. This plate ensures that when the liquid container is open no access to the sometimes aggressive treatment liquid can be obtained. When the device is rotated the liquid can flow onto the surface for treatment via the passage opening. During reverse rotation the liquid flows back again into the liquid container. The invention further comprises a method for treating a surface with a treatment liquid using a device according to the invention, which method comprises the following steps of: (a) placing the liquid in the liquid container; (b) placing the object with the surface for treatment on the opening; (c) clamping the object on the opening of the liquid container; (d) rotating the frame such that the liquid comes into contact with the surface for treatment; (e) rotating the frame further such that the liquid returns to the container; and (f) removing the object. A preferred embodiment of the method according to the invention comprises the steps of: (g) rinsing the object with a liquid, for instance water, after performing step (f ) ; (h) reducing the rinsing liquid by evaporation; (i) adding the residue of step (h) to the treatment liquid. The evaporation of the rinsing water leaves a residue which consists mainly of the treatment liquid which is used to treat the surface. This residue can therefore be added again to the liquid in the liquid container. Another preferred embodiment of the method according to the invention comprises the step of: (j) prior to performing step (b) , heating the object to a temperature which substantially corresponds with the temperature of the liquid. When the limited amount of hot liquid comes into contact with for instance a steel surface which is at room temperature, this liquid will then cool very rapidly to room temperature, whereby the action of the liquid is adversely affected. This is prevented by preheating the object. Yet another embodiment of the method according to the invention comprises the steps of: (k) checking the potential between the liquid and the surface for treatment after performing step (d) ; checking the potential; and (1) proceeding with step (e) once the potential has reached a predetermined threshold value. It has been found that the desired result of the treatment depends on the potential occurring at the moment that the liquid is removed from the object. The potential is thus related to the progress of the treatment process. The device preferably comprises exhaust means for exhausting vapour before the device is opened. Parts of the surface can be excluded from treatment by arranging masks, thereby enabling marking for aesthetic design and advertising. A special embodiment of the invention relates to a solar energy system, comprising: - a housing with a part permeable by solar radiation arranged on an upper side; - a collector which is arranged in the housing and which comprises an inclining space exposed to solar radiation via the permeable part, through which space can flow a heat transfer medium which flows in a first circulation and is coupled to a second medium circuit, wherein the first circulation takes place in a circulation tank which is filled partially with liquid and partially with vapour thereof and which operates as a circulation system which is driven by natural convection of separate evaporation and condensation; - a heat storage tank which is arranged in the second medium circuit and which is thermally coupled to a wall of the circulation tank, close to a part of the first circulation which is directed downward; and - insulation arranged in the housing at least between the space exposed to solar radiation and the heat storage tank, wherein a wall of the space exposed to solar radiation is treated in accordance with the method according to the invention. Using the treatment according to the invention a surface can be obtained which is spectrally selective. A high degree of absorption of the radiation of the sun can thus be obtained, whereby the activity of a solar energy system can be maximized. Figure 1 shows a treatment device according to the invention in perspective view with partly cut-away parts; figure 2 shows a cross-section of the device according to figure 1 in a rest position; figure 3 shows a cross-section of the device according to figure 1 in a treatment position; figure 4 shows the device of figure 1 in cross- section; figure 5 shows a solar energy system according to the invention in perspective view with partly cut-away parts; and figure 6 shows a detail of the device according to figure 5 in perspective view and in cross-section. Figure 1 shows a treatment device 1 according to the invention. This treatment device 1 has a drum-like housing 2 which is mounted rotatably on wheels 3. The wheels can be driven by means of a motor 4. In the drum housing 2 is arranged a tray 5 in which a treatment liquid 6 is placed. The underside of tray 5 is provided with a heating element 7 in order to hold the treatment liquid at a predetermined temperature. Arranged on tray 5 is a closing part 8 which is slidable between an opened position and a closed position. A product 9 for treatment is transported into drum-like housing 2 via a guide 10 and by means of a transporting device 11. In drum-like housing 2 the product 9 for treatment is pressed onto tray 5 over closing part 8 by transporting device 11 (see figure 2) . In order to treat the object 9 the drum-like housing 2 is rotated by driving wheels 3 with motor 4. Device 1 is carried into the position as shown in figure 3. In this position the closing part 8 will slide to the open position, whereby treatment liquid 6 can flow out of the tray onto object 9 and there treat a surface. Once the treatment is completed, drum-like housing 2 is rotated from the position as shown in figure 3 to the position as shown in figure 2. Object 9 is then transported out of drum-like housing 2 to a cleaning station 12 using transporting device 11. In the cleaning station the treated object 9 is sprayed from below with a cleaning liquid by means of spray nozzles 13. Air is further blown into cleaning station 12 by means of fans 14, whereby the treated object 9 is dried. The air flows via an outlet 15 to an intermediate storage tank 16 (see figure 1) . Tray 5 is provided with treatment liquid from this intermediate storage tank. Figure 5 shows a solar energy system 100 according to the invention in perspective view. This solar energy system 100 has a hollow collector 101 on which the solar radiation is incident and in which a heat transfer medium is arranged. Owing to the incident solar radiation the heat transfer medium in collector 101 will evaporate and rise upward in collector 101 and at the top be urged via pipes 102 through a heat exchanger, where the heat transfer medium once again condenses. The surface of the collector on which the solar radiation is incident is treated in an above stated manner, whereby a spectrally selective layer has been created. The heat exchanger consists of a heat storage tank consisting of elongate elements 103 and elongate flat channel plates 104 which are placed between these elements and through which the heat transfer medium runs. The condensed heat transfer medium flows further from the heat exchanger via pipes 105 to the underside of collector 101. Solar energy system 100 further has a housing which consists of a transparent upper side 106 of polycarbonate and a tray-like underside 107. Solar energy system 100 is placed with the housing directly onto roof boarding 108. In order to ensure proper sealing between housing 106,107 and the roof tiles 109 lying on roof boarding 108, the housing further has an apron part 110, which can be adjusted to the form of the roof tiles by heating. Apron part 110 is coupled slidably to the housing so that when the housing expands due to heating as a result of solar radiation the apron part 110 can displace relative to the housing, whereby cracking is prevented. In storage tank 103 is stored water which is heated by heat-exchange with the heat transfer medium. In order to prevent heat loss via roof boarding 108, an insulation structure 111 is arranged in the housing. On a part of the elongate elements 103 a heating element 112 can be further arranged which, in the case of a shortage of radiant heat, contributes toward the heating of the water in elongate elements 103.

Claims: CLAIMS 1. Device for treating a surface of an object with a treatment liquid, which device comprises: - a rotatable frame; - a liquid container arranged in the frame and having an opening which substantially corresponds in dimensions with the surface for treatment; and - clamping means for clamping the object on the opening of the liquid container such that the surface for treatment is directed toward the container and closes the opening. 2. Device as claimed in claim 1, wherein heating means are arranged on the liquid container. 3. Device as claimed in claim 2, wherein the heating means hold the liquid at about 70°C. 4. Device as claimed in claim 1, comprising control means for controlling the treatment process, which control means are galvanically connected to both the surface for treatment and the liquid. 5. Device as claimed in claim 4, wherein the control means apply a galvanic potential between the liquid and the surface for treatment. 6. Device as claimed in claim 1, wherein the treatment liquid comprises chromic acid and/or sulphuric acid. 7. Device as claimed in claim 1, wherein a plate is arranged in the opening of the container such that a passage opening is kept clear between at least one side of the opening and one side of the plate. 8. Method for treating a surface with a treatment liquid using a device as claimed in claim 1, which method comprises the following steps of: (a) placing the liquid in the liquid container; (b) placing the object with the surface for treatment on the opening; (c) clamping the object on the opening of the liquid container; (d) rotating the frame such that the liquid comes into contact with the surface for treatment; (e) rotating the frame further such that the liquid returns to the container; and (f) removing the object. 9. Method as claimed in claim 8, further comprising the steps of: (g) rinsing the object with a rinsing liquid after performing step (f ) ; (h) reducing the rinsing liquid by evaporation; (i) adding the residue of step (h) to the treatment liquid. 10. Device as claimed in claim 8, comprising the step of : (j) prior to performing step (b) , heating the object to a temperature which substantially corresponds with the temperature of the liquid. 11. Device as claimed in claim 8, comprising the steps of : (k) checking the potential between the liquid and the surface for treatment after performing step (d) ; checking the potential; and (1) proceeding with step (e) once the potential has reached a predetermined threshold value. 12. Solar energy system, comprising: - a housing with a part permeable by solar radiation arranged on an upper side; - a collector which is arranged in the housing and which comprises an inclining space exposed to solar radiation via the permeable part, through which space can flow a heat transfer medium which flows in a first circulation and is coupled to a second medium circuit, wherein the first circulation takes place in a circulation tank which is filled partially with liquid and partially with vapour thereof and which operates as a circulation system which is driven by natural convection of separate evaporation and condensation; - a heat storage tank which is arranged in the second medium circuit and which is thermally coupled to a wall of the circulation tank, close to a part of the first circulation which is directed downward; and - insulation arranged in the housing, characterized in that a wall of the collector is treated in accordance with the method as claimed in any of the claims 8-11.

Inventors: BERTELS AUGUSTINUS WILHELMUS M, BERTELS, AUGUSTINUS, WILHELMUS, MARIA
Applicants: BERTELS AUGUSTINUS WILHELMUS M, INVENTUM B V, BERTELS, AUGUSTINUS, WILHELMUS, MARIA, INVENTUM B.V.
Application year: 2001
Main classification: C23C22
IPC codes: C23C22, F24J2