Device for surface treatment of workpieces in a pipeline

Abstract

The present invention relates to a device for surface treatment of workpieces in a production line, said device having a positioning frame (1) for the workpieces to be treated, said positioning frame having a coupling (3) for a positioning drive (4). In order to increase productivity independently of the surface treatment without having to tolerate losses in the surface quality of the coating, it is proposed here that a hermetically enclosed housing (2) is supported on the positioning frame (1), said housing having connecting lines (5) for exchanging working materials with different working material supply units (6) arranged along the production line.

Description

Field of the Invention

[0001] The present invention relates to a device for surface treatment of workpieces in a production line, the device having a positioning frame for the workpieces to be treated, the positioning frame having a coupling for a positioning drive. Background Art

[0002] A device for surface treatment, in particular for coloring workpieces, is known from document US 20170246652 A1. The device consists of a container which can be sealed off by means of a lid. The container is penetrated by a plurality of connecting lines through which fluids or dispensed surface treatment media can be introduced or discharged and overpressure or negative pressure can be applied. In addition, the container can be heated or cooled by means of temperature regulating elements arranged on the outer periphery. Although a high surface treatment quality can be achieved by means of the complex design and equipment of the device, the coating process carried out in this device reaches its limits especially at higher production rates. Therefore, the production rate can only be increased by operating a plurality of devices in parallel, which, however, results in high investment costs due to the technical complexity of the devices.

[0003] In order to increase the production rate during surface treatment of workpieces, a production line is disclosed in document US 6471837. The production line includes a central distribution chamber which guides the workpieces through different sealable sub-chambers. The sub-chambers can be evacuated and can be equipped with different devices, such as cathodic atomizers and temperature regulating elements, depending on the surface treatment process. However, disadvantageously, such a production line is extremely inflexible with respect to different surface treatment processes because the sub-chambers are fixedly connected to the distribution chamber. In addition, relatively high operating costs are incurred on the one hand due to the relatively large design of the sub-chambers in order to create uniform operating conditions, for example, by evacuation or temperature regulation, throughout the sub-chambers, and on the other hand, the quality of the coating is impaired due to the limited accessibility of the coating medium and the resulting insufficient application.

[0004] For particularly large workpieces, such as automobile bodies, electrochemical dipping methods are known from the prior art. For this purpose, the automobile body is arranged on a positioning frame which can be rotated by a positioning drive and the automobile body is thus immersed in an electrically conductive dipping paint. By applying a DC voltage between the automobile body as the cathode and the anode, the dipping paint is deposited on the automobile body and adheres there. However, mainly during longer production cycles, the quality of the painting is reduced during the course of the day due to contamination of the dipping paint and the resulting change in the particle concentration in the dipping paint bath. In addition, in such dipping methods, for example, a two-phase mixture is produced due to the entry of air bubbles, which also reduces the surface treatment quality. Summary of the Invention

[0005] The technical problem to be solved by the present invention is thus to propose a method and a device for surface treatment of the aforementioned type, which device or method increases productivity regardless of the type of surface treatment, without having to tolerate a loss in the surface quality of the coating in this case.

[0006] The technical problem is solved according to the invention in such a way that a hermetically sealable housing is supported on the positioning frame, which housing has connecting lines for exchanging working materials with different working material supply units arranged along the production line.

[0007] Due to this measure, all the method steps required for surface treatment can be carried out in a housing that is enclosed from the surrounding environment. The method steps include transporting the workpiece through an assembly line, pre-treating the workpiece, applying different working materials, such as materials for surface treatment, to the workpiece, hardening the materials for surface treatment, etc. The housing is dimensioned according to the workpiece in such a way that the housing provides sufficient space for accommodating the workpiece. Nevertheless, the environment (pressure, temperature, humidity, etc.) enclosed by the housing can be controlled as energy-efficiently as possible, and thus precise control of the process conditions can be achieved. According to the invention, the control of the enclosed environment is achieved through connecting pipelines, which enable the housing to exchange working materials with the working material supply units arranged along the assembly line. The possible active process components in the housing itself are kept to a minimum. The housing is constructed as a reaction chamber for surface treatment of the workpiece and for controlling the environment of the housing. In principle, materials that can be regarded as working materials are materials for pre-treating the workpiece, such as cleaning agents, materials for surface treatment, such as liquid paint or powder paint, nanoparticles, and also materials that affect the environment, such as hot air, water vapor, etc. If the housing is equipped with simple electrical components, such as temperature regulating elements, then electric current is used as the working material. In corresponding designs of the housing, electromagnetic rays for controlling the environment or the workpiece can be used as the working material, which in this case are not guided through the connecting pipelines. Since the connecting pipelines are not only suitable for filling the housing with working materials, but also for emptying the housing, a negative pressure or vacuum can be generated in the housing by sucking air as the working material. Since the hermetically sealed housing is used according to the invention, a uniform and clean reaction chamber is produced, which additionally improves the working safety for possible operators by eliminating the escaping working material vapors. The working materials are provided by the working material supply units arranged along the assembly line, which include conveying devices for the working materials and provide different working materials according to the type of surface treatment. The positioning of the frame and the conveyance of the housing supported on this positioning frame are achieved by a positioning drive, which is connected to the positioning frame by a coupling. The positioning drive can be designed, for example, as a cable drive or a rail drive independently of the positioning frame and is only connected to the positioning frame by a coupling. The positioning drive can also be integrated into the positioning frame or, in a particularly preferred embodiment, form a unit independent of the positioning frame.

[0008] The housing can also be used for immersion and removal in the impregnation process. For this purpose, the workpiece can be arranged in the housing and the housing can be evacuated through a connecting line. The evacuated housing can be immersed in the paint dipping tank by a positioning drive, and then the workpiece can be conveyed from the housing through the paint dipping tank to a second housing by a transport device. Subsequently, the second housing can be closed, evacuated and conveyed out of the paint dipping tank by the positioning drive. By immersing or removing the workpiece in the evacuated housing, the entry of air bubbles can be prevented and thus the formation of an undesirable two-phase mixture that reduces the surface treatment quality can be avoided.

[0009] In order to position the housing unobstructed or convey the housing through the production line and nevertheless be able to couple it quickly and reliably to the process material supply unit, it is proposed here that the positioning frame is designed as a connecting line for fluid connection to the housing. The connecting line is thus not arranged slackly on the housing but is guided through the frame. In a particularly expedient design variant of the invention, the frame itself can be the connecting line, so that it is possible to dispense with an independent connecting line between the process material supply unit and the housing and thus reduce the required manufacturing effort. In order to protect against the influence of the process material, for example against oxidation, the frame can have a corresponding inner coating. Irrespective of whether the connecting line is guided through the frame or consists of the frame, it is possible to prevent twisting or entanglement of the connecting line and to access the housing unobstructed, for example for inspection operations.

[0010] It is proposed here that the connecting line extends through the coupling for the positioning drive, thereby enabling the housing to be coupled quickly and reliably to the process material supply unit without restricting the possible movement of the housing for dispensing the process material. The mechanical connection and the process material supply can thus be effected via a connection point that is independent of the relative position of the housing or the positioning frame in terms of its relative position with respect to the process material supply unit. In a corresponding design variant of the coupling, the connecting line is thus only subject to a low bending moment, thereby achieving a particularly high service life of the connecting line.

[0011] In order to be able to move the positioning frame according to the invention together with the housing supported on it between the individual process material supply units when coupling the positioning drive and to be able to couple it simply at each process material supply unit, it is proposed here that the connecting line extends through the positioning drive. The drive shaft of the positioning drive connected to the positioning frame can, for example, be designed hollow so that the connecting line can be guided from the positioning frame through the positioning drive within this drive shaft.

[0012] If the environment in the housing is to be controlled during loading of the working material for surface treatment, the positioning frame may have a coupling shaft connecting two mutually opposed coupling elements, and the coupling shaft for the two coupling elements is configured as two mutually separated connecting line sections for different working materials. Thus, one connecting line section can be connected to a first working material supply unit that supplies the interior space of the housing with the working material for surface treatment or surface pretreatment of the workpiece, while the other connecting line section can be connected to a second working material supply unit that evacuates the housing, supplies temperature-regulating fluid, and / or air humidity. Thereby, two processing steps can be carried out at one processing position during connection to the two mutually opposed working material supply units.

[0013] In order to apply the working material completely to the workpiece and prevent different particles in the working material from depositing, it is proposed here that the coupling shaft connecting the two mutually opposed coupling elements be configured as a rotating shaft for the positioning frame, and the rotating shaft is used to evenly distribute the working material in the housing. The positioning drive of the positioning frame can not only be used to move the housing translationally through the production line, but is also provided for rotating the housing about the coupling shaft. For this purpose, two separate positioning drives or a single positioning drive can be provided, and this single positioning device realizes both the translational movement of the housing and the rotation about the coupling shaft as the horizontal rotating shaft.

[0014] The positioning frame has a chassis independent of the positioning drive, whereby the housing can be conveyed through the production line in an energy-saving manner. The positioning drive can be guided on a track, for example, while the positioning frame can have a set of rollers to carry the load, whereby the load on the coupling elements can be relieved and the service life of the coupling elements can be increased.

[0015] The height of the upper part of the housing exceeds the height of the lower part of the housing supported on the positioning frame, thereby creating particularly favorable conditions for transporting the housing to the workpiece to be coated. The positioning frame preferably forms a unit with the lower part of the housing, the workpiece is placed on the unit and fixed to the positioning frame within the lower part of the housing, and then the upper part of the housing is placed on the lower part of the housing and thereby seals the housing.

[0016] In order to be able to supply power to the possible components arranged in the interior space of the housing without affecting the detachable nature of the housing, it is appropriate that the upper part of the housing can be connected to the lower part of the housing via a flange with electrical contacts around the housing. Nevertheless, the contact part is still protected from accelerated corrosion due to possible working materials or other environmental influences in the interior space of the housing by the arrangement according to the invention.

[0017] In order to reliably exchange the working material between the housing and the working material supply unit in terms of process, the upper part of the housing may have an input valve for the working material connected to the connecting pipeline, and the lower part of the housing may have an output valve for the working material connected to the connecting pipeline. Thereby, the working material can be evenly applied to the workpiece, and at the same time, the working material can be sucked away without leaving residues. The input valve can be changed according to the surface treatment process. If a device for powder coating is used, the input valve can, for example, have a rotary bell, finger nozzles, impact plate nozzles (Pralltellerdüse) and / or flat jet nozzles.

[0018] The positioning frame is embedded in the lower part of the housing, thereby not only creating particularly compact construction conditions, but also enabling the liquid working material to be transported out of the housing in an advantageous manner in the corresponding design structure of the connecting pipeline.

[0019] The invention also relates to a method for surface-treating a workpiece in a production line, wherein the workpiece is moved on a positioning frame by a positioning drive. In order to minimize the resource consumption for the method without reducing the productivity or manufacturing quality, it is hereby proposed that the workpiece be arranged in a housing that can be sealed and closed, and then the closed housing supported on the positioning frame is gradually transported by the positioning drive to different working material supply units of the production line, coupled to different working material supply units respectively, loaded with the working material and decoupled again. Depending on the type of surface treatment, the working material supply unit can include different working materials. If the method for surface treatment is, for example, electrophoretic deposition, the first working material supply unit can load the interior space of the housing with a cleaning agent to remove grease or paint residues adhering to the workpiece. After removing the cleaning agent by the working material supply unit, the housing is decoupled and the housing is transported by the positioning drive of the positioning frame to other working material supply units. The working material supply unit, for example, fills the interior space of the housing with an electrolyte to generate a conversion layer on the workpiece, for example, and then empties the interior space of the housing again. The third working material supply unit can input a conductive liquid paint for coating the workpiece into the interior space of the housing. For example, a DC voltage field is applied between the workpiece connected as the cathode and the anode arranged in the housing, whereby the paint particles are deposited on the workpiece. Of course, the workpiece can also be connected as the anode. In this case, the cathode must be arranged in the housing. In the last method step, the applied paint is hardened. This can be achieved, for example, by inputting hot air by other working material supply units or by a temperature regulating element. Since the device has a plurality of connecting pipelines for simultaneously loading different working materials, the process conditions, namely temperature, pressure and air humidity, can be influenced in each method step.

[0020] In order to apply the working material evenly at hard-to-reach locations of the workpiece, the housing loaded with the working material can be rotated about a horizontal axis of rotation. The rotation can be performed before, during and / or after loading.

[0021] In order to make the working material applied to the workpiece for surface treatment harden uniformly and energy-saving, it is suitable that at least one working material has particles that can be excited dielectrically or inductively, and the housing designed to be electromagnetically permeable is guided through the electromagnetic field to heat the particles. In principle, the particles can be part of the working material for surface treatment, such as metal pigments in powder paint or liquid paint. Alternatively, in other method steps, the particles that can be excited dielectrically or inductively can be transported into the housing as part of the hardener. If the particles are excited by the electromagnetic radiation of the electromagnetic field, the particles will heat up. The heat generated thereby can be used to fix the paint, that is, evaporate the solvent contained in the liquid paint or harden the powder paint. It has been proven that electromagnetic fields with a frequency of 30 kHz to 300 MHz are particularly suitable for exciting the particles located in the housing due to their sufficient penetration depth and generating the required curing temperature of preferably 150 to 200 ° C. By not heating the workpiece according to the method of the present invention, but only heating the layer containing the particles that can be excited dielectrically or inductively, the desired temperature conditions can be quickly reached and accurately adjusted. If the particles are exposed to an electromagnetic field for approximately 5 to 50 minutes, different lacquers can be completely fixed. Preliminary calculations show that 90% of the drying energy can be saved compared to drying methods known from the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The technical solution of the present invention is exemplarily shown in the accompanying drawings. In the accompanying drawings:

[0023] Figure 1 A top view of a production line having a plurality of devices for surface treatment according to the invention and a working material supply unit is shown,

[0024] Figure 2 The schematic cross-sectional view obtained by cutting along the cutting line II-II is shown in an enlarged size.

[0025] Figure 3 A top view of a production line is shown, which has two devices according to the invention for surface treatment and a transmitter for generating an alternating electromagnetic field, and

[0026] Figure 4 The figure shows a side view of a production line having a plurality of devices for surface treatment and a working material supply unit according to the invention. DETAILED DESCRIPTION

[0027] A device for surface treatment of workpieces according to the present invention, in particular Figure 2 has a housing 2 supported on a positioning frame 1 as shown. In order to be able to convey the housing 2 along the Figure 1 shown pipeline, the positioning frame 1 is connected to a positioning drive 4 by a coupling member 3. It can also be seen from Figure 2 that two positioning drives 4 can also be provided, and these two positioning drives are respectively connected to the positioning frame 1 by coupling members 3. The housing 2 can be hermetically closed, thereby creating a reaction chamber that is closed relative to the surrounding environment. By keeping the reaction space as small as possible, a particularly resource-saving surface treatment can be achieved, because the process conditions can already be influenced and optimized by a smaller flow of working material. The connection pipeline 5 is used to control the environment in the reaction chamber or control the process conditions and load the reaction chamber with the working material for surface treatment. The connection pipeline fluid-technically connects the housing 2 to a working material supply unit 6 arranged along the pipeline. The working material supply unit can supply different working materials to the housing 2 according to the type of surface treatment, thereby enabling the pipeline to be used for different surface treatment processes without having to take costly measures in terms of design.

[0028] As particularly disclosed in Figure 2 , the positioning frame 1 itself can be a component of the connection pipeline 5, thereby achieving a simple fluid connection between the housing 2 and the working material supply unit 6. Due to these measures, there is no connection pipeline 5 that exposes the independent positioning, conveyance, or accessibility that may damage the housing 2.

[0029] In order to enable the housing 2 to be quickly coupled to the working material supply unit 6 and still achieve the free movement of the housing 2, the connection pipeline 5 is guided through the coupling member 3 and the positioning drive 4. The positioning drive 4 can be supported on a track 7, and the positioning device gradually conveys the device through the pipeline.

[0030] If multiple working materials need to be supplied to the housing 2 simultaneously, or if the process conditions, such as pressure, temperature, and / or humidity, need to be influenced simultaneously during the supply of the working material without compromising the free mobility of the housing 2, the positioning frame 1 can have a coupling shaft 8 that mechanically connects the two coupling members 3. The coupling shaft 8 forms two connection pipeline sections separated by a closed valve 9 here.

[0031] The coupling shaft 8 is a horizontal rotation shaft here, whereby the housing 2 can be rotated by a rotation drive 10 of the positioning drive 4. Thereby, the possible working materials can be evenly distributed in the inner space of the housing, that is, in the reaction chamber, and evenly applied to the workpiece (not shown).

[0032] To support the movement of the device according to the invention along the production line, the positioning frame 1 may have a chassis 11 including rollers.

[0033] If the height H of the upper housing part 12 exceeds the height h of the lower housing part 13, the housing 2 and the workpiece can be transported in a particularly simple manner.

[0034] Therefore, although the connection between the upper housing part 12 and the lower housing part 13 is detachable, a reliable electrical contact can still be achieved without any possible cable hindering the free positioning of the housing 2. The upper housing part 12 and the lower housing part 13 are interconnected by a flange 14. The flange 14 has electrical contacts (not shown) for this purpose.

[0035] To reliably input or output the working material to or from the housing 2 during operation, the upper housing part 12 has an input valve 15 connected to the connecting line 5 and the lower housing part has an output valve 16. In this embodiment, the shut-off valve 9 also assumes the function of the output valve 16. The positioning frame 1 can be inserted into the lower housing part 13 together with the output valve 16.

[0036] Figure 3 A transmitter 17 for generating an alternating electromagnetic field is shown. Particles that can be dielectrically or inductively excited, such as metal pigments in powder paint or liquid paint, or possible nanoparticles, contained in the working material are excited by this transmitter and are thus heated. The heat generated can be used to harden the working material applied to the workpiece.

[0037] Figure 4 For example, the feasibility of the housing 2 rotating about a horizontal axis of rotation is shown. The dashed line 18 shows different filling levels of the working material when it is filled or pumped out by the working material supply unit 6.

Claims

1. An apparatus for surface treatment of workpieces in an assembly line, the apparatus having a positioning frame (1) for the workpieces to be treated, the positioning frame having a coupling (3) for a positioning drive (4). Characterized in that a housing (2) that can be sealed is supported on the positioning frame (1), and all method steps required for surface treatment are carried out in the housing that is closed off from the surrounding environment. The housing has a first connecting line (5) for exchanging working materials with different working material supply units (6) arranged along the assembly line, wherein the positioning frame (1) is configured as a second connecting line for fluid connection with the housing (2).

2. The apparatus according to claim 1, Characterized in that the second connecting line extends through the coupling (3) for the positioning drive (4).

3. The apparatus according to claim 1, Characterized in that the second connecting line extends through the positioning drive (4).

4. The apparatus according to any one of claims 1 to 3, Characterized in that the positioning frame (1) has a coupling shaft (8) connecting two mutually opposed couplings (3), and the coupling shaft for the two couplings (3) is configured as two mutually separated connecting line sections for different working materials.

5. The apparatus according to any one of claims 1 to 3, Characterized in that the coupling shaft connecting two mutually opposed couplings (3) is configured as a rotation shaft for the positioning frame (1), and the rotation shaft is used to evenly distribute the working materials in the housing (2).

6. The apparatus according to any one of claims 1 to 3, Characterized in that the positioning frame (1) has a chassis (11) independent of the positioning drive (4).

7. The apparatus according to any one of claims 1 to 3, Characterized in that the height (H) of the upper housing part (12) exceeds the height (h) of the lower housing part (13) supported on the positioning frame (1).

8. The apparatus according to claim 7, Characterized in that the upper housing part (12) can be connected to the lower housing part (13) by means of a flange (14) around the housing (2) that has electrical contacts.

9. The apparatus according to claim 7, Characterized in that the upper housing part (12) has an input valve (15) for working materials connected to the first connecting line (5), and the lower housing part (13) has an output valve (16) for working materials connected to the second connecting line.

10. The apparatus according to claim 7, Characterized in that the positioning frame is embedded in the lower housing part (13).

11. A method for surface treatment of workpieces in an assembly line, the workpieces moving on a positioning frame (1) by means of a positioning drive (4). Characterized in that The workpiece is arranged within a housing (2) that can be sealed, the housing having a first connecting line, and the sealed housing (2) supported on the positioning frame (1) is gradually conveyed by the positioning drive (4) to different working material supply units (6) of an assembly line, is coupled to different working material supply units respectively, is loaded with working material and is decoupled again, wherein the positioning frame (1) is configured as a second connecting line for fluid connection with the housing (2).

12. The method according to claim 11, characterized in that the housing (2) loaded with working material is rotated about a horizontal axis of rotation.

13. The method according to claim 11 or 12, characterized in that at least one working material has particles that can be excited dielectrically or inductively, and the housing (2) designed to be electromagnetically permeable is guided through an electromagnetic field in order to heat the particles.

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