Equipment for surface treatment of workpieces on a manufacturing line

Abstract

An apparatus for surface treating workpieces in a production line is described, which comprises a positioning frame (1) for the workpieces to be treated, which has a connecting member (3) for a positioning drive (4). In order to enable an increase in the production rate regardless of the type of surface treatment without having to accept any loss in the surface quality of the coating, it is proposed that a sealable capsule (2) is supported on the positioning frame (1), and the capsule (2) has connecting lines (5) for exchanging the operating medium with various operating medium supply units (6) arranged along the production line.

Description

[Technical field]

[0001] The present invention relates to an apparatus for surface treating workpieces in a production line, which comprises a positioning frame having a connection member for a positioning drive for the workpiece to be treated. [Background technology]

[0002] In US20170246652, an apparatus for surface treatment, in particular coloring, of workpieces is known. The apparatus consists of a container, which can be closed by a lid. In this case, a number of connecting lines pass through the container, via which a fluid or powdery surface treatment agent can be introduced or removed, and positive or negative pressure can be applied. Furthermore, the container can be heated or cooled via a temperature control element attached to the outside of the periphery. Although a high quality of the surface treatment can be achieved due to the complex configuration and equipment of the apparatus, the coating method carried out in this apparatus reaches its limits, especially at relatively high production rates. The production rate can therefore only be increased by operating several apparatuses in parallel, which, however, leads to huge investment costs due to the complex technology of the apparatus.

[0003] In order to increase the production rate when surface treating workpieces, a production line is disclosed in US Pat. No. 6,471,837. This production line has a central distribution chamber, which guides the workpieces through various sealable subchambers. The subchambers can be evacuated and, depending on the surface treatment method, are equipped with various devices, for example cathode sprayers and temperature adjustment elements. However, a disadvantage is that such a production line is very inflexible for different surface treatment methods, since the subchambers are rigidly connected to the distribution chamber. Furthermore, due to the large configuration of the subchambers, on the one hand, the operating costs are relatively high to create uniform operating conditions throughout the subchambers, for example by evacuation or temperature adjustment, and on the other hand, due to only limited access to the products and therefore only an insufficient supply of coating agent, the quality of the coating is impaired.

[0004] For particularly large workpieces, such as car bodies, electrochemical dipping methods are known in the prior art. For this, the car body is arranged in a rotatable positioning frame via a positioning drive and is thus dipped into the conductive dipping paint. By applying a direct voltage between the car body acting as the cathode and the anode, the dipping paint is precipitated on the car body and adhered there and is retained. However, particularly in large production cycles, this leads to a deterioration in the quality of the coating over time due to contamination of the dipping paint and changes in the particle concentration in the dipping paint bath. Furthermore, in such dipping methods, two-phase mixing occurs, for example due to the introduction of air bubbles, which also reduces the surface treatment quality. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US Patent Application Publication No. 20170246652 [Patent Document 2] U.S. Patent No. 6,471,837 Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is therefore to propose an apparatus and method for surface treatment of the type mentioned at the outset, which allows an increase in production rate regardless of the type of surface treatment, without having to accept any loss in the surface quality of the coating. [Means for solving the problem]

[0007] The present invention achieves this set objective in that a capsule that can be tightly closed is supported on a positioning frame, the capsule having connecting lines for exchanging the operating medium with various operating medium supply units arranged along the production line.

[0008] On the basis of such measures, all the method steps required for the surface treatment, such as the transport of the workpieces through the production line, the pretreatment of the workpieces, the application of various operating media, such as surface treatment substances, crosslinking of the surface treatment substances, etc., can be carried out in a capsule closed off from the surrounding environment. In this case, depending on the workpiece, the dimensions of the capsule are set in such a way that the capsule provides sufficient space to accommodate the workpieces, but nevertheless allows the most energy-saving operation possible of the atmosphere enclosed by the capsule (pressure, temperature, humidity, etc.) and thus the precise control of the process conditions. According to the invention, the operation of the closed atmosphere is carried out through a connecting line that allows the exchange of the operating medium between the capsule and an operating medium supply unit arranged along the production line. Possibly present active method elements in the capsule itself are limited to a minimum. The capsule is configured as a reaction chamber for the surface treatment of the workpieces and the operation of the atmosphere in the capsule. In principle, the operating medium can be considered to be substances for the pretreatment of the workpieces, such as cleaning agents, substances for the surface treatment, such as liquid or powder paints, nanoparticles, as well as substances that influence the atmosphere, such as hot air, water vapor, and the like. When the capsule is equipped with simple electrical elements, such as, for example, temperature control elements, electric current is used as the operating medium. When the capsule is accordingly designed, the atmosphere or electromagnetic radiation for manipulating the workpiece, which is not guided through the connecting lines here, is used as the operating medium. The connecting lines are suitable not only for filling the capsule with the operating medium, but also for emptying it, so that a negative pressure or vacuum can be created in the capsule by sucking in air as the operating medium. Thus, based on the use of the sealable capsule according to the invention, a homogeneous and clean reaction chamber is formed, which additionally increases the working safety for the possibly present operator by eliminating the outflow of operating medium vapors. The operating medium is provided by an operating medium supply unit, which is arranged along the production line, has a conveying device for the operating medium and provides different operating media depending on the type of surface treatment.The transport of the positioning frame together with the capsules supported against it takes place via a positioning drive which is connected to the positioning frame via a coupling element, which can be configured, for example, as a cable drive or rail drive, regardless of the positioning frame, and can be connected to the positioning frame exclusively via a coupling element, and which can also be integrated into the positioning frame or, in a particularly preferred embodiment, form a separate unit from the positioning frame.

[0009] The capsules can also be used for the immersion and removal processes in the dipping method. For this purpose, the workpieces are placed in the capsule, which can be evacuated via a connecting line. The evacuated capsule can be immersed in a dipping bath via a positioning drive, after which the workpieces are transferred from this capsule through the dipping bath via a conveying device to a second capsule. Following this, the second capsule can be closed, evacuated and transferred out of the dipping bath via the positioning drive. Immersion or removal of the workpieces in an evacuated capsule can prevent the introduction of air bubbles and thus the formation of an undesirable two-phase mixture, which reduces the quality of the surface treatment.

[0010] In order to allow an unhindered positioning or transport of the capsules through the production line and nevertheless a fast and reliable connection to the operating medium supply unit, it is proposed that the positioning frame forms a connecting line for a flow connection with the capsule. The connecting line is therefore not arranged loosely on the capsule but is guided through the frame. In a particularly structurally preferred embodiment of the invention, the frame itself can be the connecting line, so that a separate connecting line between the operating medium supply unit and the capsule can be avoided and thus the required manufacturing effort can be reduced. For protection against the operating medium, for example against oxidation, the frame can have a corresponding inner coating. Regardless of whether the connecting line is guided through the frame or is formed by the frame, it can be prevented from twisting or entangling, and an unhindered approach to the capsule, for example for inspection operations, can be achieved.

[0011] In order to ensure that the capsule can be connected to the operating medium supply unit quickly and reliably without any restriction of the possible movement of the capsule for dispensing the operating medium, it is recommended that the connecting line is guided through the connecting element to the positioning drive. Thus, both the mechanical connection and the operating medium supply can be made via the connection point. The connection point does not depend on the relative position of the capsule or the positioning frame in relation to the operating medium supply unit. Thus, when the connecting element is appropriately designed, the connecting line is only subjected to small bending moments, which results in a particularly long service life of the connecting line.

[0012] In order that the positioning frame according to the invention, together with the capsules supported thereon, can be moved when the positioning drive is connected between the individual operating medium supply units and can be easily connected at each operating medium supply unit, it is proposed that the connecting lines are guided through the positioning drive. For example, the drive shaft of the positioning drive, which is connected to the positioning frame, can be designed hollow, so that the connecting lines can be guided through the positioning drive in this drive shaft.

[0013] When it is desired to manipulate the atmosphere in the capsule while the working medium for the surface treatment is being supplied, the positioning frame may have a connecting shaft which connects two oppositely located connecting members, the connecting shaft forming two separate connecting line sections for different working media for both connecting members. Thus, the connecting line section can be connected to a first working medium supply unit which supplies the inner space of the capsule with the working medium for the surface treatment or surface pre-treatment of the workpiece, while the other connecting line section can be connected to a second working medium supply unit which evacuates the capsule and supplies it with a temperature-regulating fluid and / or moisture. This allows two processing steps to be performed in one processing position, in particular during connection to two oppositely located working medium supply units.

[0014] In order to achieve a complete application of the working medium on the workpieces and to prevent the accumulation of various particles in the working medium, it is proposed that the connecting shaft connecting the two opposite connecting parts forms a rotation axis relative to the positioning frame in order to distribute the working medium evenly in the capsule. A positioning drive of the positioning frame can therefore be provided both for the translational movement of the capsule through the production line and for the rotation of the capsule about the connecting shaft. For this purpose, two separate positioning drives can be provided or a single positioning drive can be provided, which allows both the translational movement of the capsule and the rotation about the connecting shaft as a horizontal rotation axis.

[0015] If the positioning cage has a running platform independent of the positioning drive, an energy-saving transport of the capsules through the production line can be achieved. The positioning drive can be guided, for example, on rails, while the running platform of the positioning cage can have a roller set for load equalization, which reduces the load on the connecting members and increases their service life.

[0016] Particularly favorable conditions for feeding the capsule with the workpiece to be processed are obtained when the height of the capsule upper part exceeds the height of the capsule lower part supported by the positioning frame, in which case the positioning frame preferably forms a unit together with the capsule lower part, on which the workpiece is placed and fixed by the positioning frame in the capsule lower part, after which the capsule upper part is placed on the capsule lower part and thus the capsule is sealed.

[0017] It is recommended that the upper part of the capsule can be connected to the lower part of the capsule via a flange that extends around the capsule and has electrical contacts, so that the supply of power to any element placed in the capsule interior can be realized without impairing the removability of the capsule. Nevertheless, the contacts are protected by the device according to the invention from corrosion promoted by the influence of the operating medium or other surroundings possibly present in the capsule interior.

[0018] To ensure a reliable exchange of the operating medium between the capsule and the operating medium supply unit for the process, the capsule upper part may have an inlet valve for the operating medium, which is connected to the connecting line, and the capsule lower part may have an outlet valve for the operating medium, which is connected to the connecting line. This allows an even application of the operating medium to the workpiece and at the same time a residue-free suction of it. The inlet valve may be different depending on the surface processing method. When the device is used for powder coating, the inlet valve may have, for example, a rotary atomizer, a finger nozzle, a plate nozzle and / or a flat jet nozzle.

[0019] When the positioning cage passes through the lower capsule part, not only are particularly compact construction conditions achieved, but also, if the connecting lines are appropriately designed, the liquid operating medium can be conveyed out of the capsule in an advantageous manner.

[0020] The invention also relates to a method for surface treatment of workpieces which are moved by a positioning drive via a positioning frame in a production line. In this case, in order to minimize the resource consumption for the method without reducing the production rate or the production quality, it is proposed to place the workpieces in a sealable capsule and then transport the closed capsule supported in the positioning frame stepwise by the positioning drive to various operating medium supply units of the production line, connect each time, supply the capsule with operating medium and detach the capsule again. Depending on the type of surface treatment, the operating medium supply units can have various operating media. When the method for surface treatment is, for example, an electrophoretic deposition method, the first operating medium supply unit can supply the capsule interior with a cleaning agent in order to remove grease or paint residues adhering to the workpieces. After the cleaning agent has been removed by the operating medium supply unit, the capsule is detached and transported by the positioning drive of the positioning frame to another operating medium supply unit. The other operating medium supply unit fills the capsule interior with an electrolyte, for example to generate a conversion layer on the workpiece, and subsequently empties the capsule interior again. The third operating medium supply unit can supply the capsule interior with an electrically conductive liquid paint for coating the workpiece. A direct current voltage field is then applied between the workpiece, for example connected as a cathode, and an anode mounted in the capsule, which causes paint particles to precipitate on the workpiece. There is no need to explain further that the workpiece can be connected as an anode. In this case, the cathode must be arranged in the capsule. In the final method step, the applied paint is cross-linked. This can be done, for example, by supplying hot air from a separate operating medium supply unit or by means of a temperature control element. As the device has several connecting lines for the simultaneous supply of various operating media, the process conditions, i.e. temperature, pressure and humidity, can be influenced during each method step.

[0021] To ensure that the operating medium is applied as evenly as possible to difficult-to-reach locations on the workpiece, the capsule filled with the operating medium can be rotated about a horizontal pivot axis before, during and / or after the supply.

[0022] In order to achieve uniform and energy-saving cross-linking of the working medium applied to the workpiece for surface treatment, it is recommended that at least one working medium has dielectrically or inductively excitable particles, and that the capsule, which is configured to be electromagnetically transparent, is guided through the electromagnetic field in order to heat the particles. In principle, the particles can already be part of the working medium for surface treatment, as is the case, for example, with metal pigments in powder paints or liquid paints. Alternatively, the dielectrically or inductively excitable particles can be conveyed into the capsule as part of the hardener in a separate method step. There, the particles are excited and thus heated by the electromagnetic radiation of the electromagnetic field. The heat thus generated can be used for fixing the paint, and thus for evaporating the solvent contained in the liquid paint, or for cross-linking the powder paint. In this case, it has been found that an electromagnetic field having a frequency of 30 kHz to 300 MHz is particularly well suited, due to its sufficient penetration depth, to excite the particles present in the capsule and to generate the desired hardening temperature, preferably between 150 ° C and 200 ° C. By the method according to the invention, only the layer containing the dielectrically or inductively excitable particles is heated, and not the workpiece, so that the desired temperature conditions can be achieved quickly and precisely controlled. Complete fixing of various paints can be achieved when the particles are exposed to the electromagnetic field for about 5 to 50 minutes. Initial calculations show that in this case 90% of the drying energy can be saved compared to the drying methods known in the prior art.

[0023] The drawings illustrate the subject matter of the invention. [Brief description of the drawings]

[0024] [Figure 1] FIG. 2 shows a plan view of a production line with a number of surface treating devices and a number of operating medium supply units according to the present invention; [Diagram 2] The cross section along line II-II is shown in an enlarged schematic diagram. [Diagram 3] FIG. 1 shows a plan view of a production line having two surface treating devices according to the present invention and one emitter for generating an alternating electromagnetic field. [Figure 4] FIG. 2 shows a side view of a production line with a number of surface treating devices and a number of operating medium supply units according to the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] The device for surface treatment of workpieces according to the invention, as can be seen in particular in FIG. 2, has a capsule 2 supported on a positioning frame 1. The positioning frame 1 is connected to a positioning drive 4 via a connecting element 3 so that the capsule 2 can be transported along the production line shown in FIG. 1. As can be further seen from FIG. 2, two positioning drives 4 may be provided, each of which is connected to the positioning frame 1 via a connecting element 3. The capsule 2 is sealable, so that a reaction chamber closed off from the surrounding environment is formed. By keeping the reaction chamber as small as possible, a particularly resource-saving surface treatment can be realized, since the process conditions can already be influenced and optimized by means of a small flow of the operating medium. The manipulation of the atmosphere in the reaction chamber or the control of the process conditions and the supply of the operating medium for surface treatment to the reaction chamber are carried out via a connecting line 5. The connecting line 5 connects the capsule 2 in terms of flow to an operating medium supply unit 6 arranged along the production line. The operating medium supply unit can supply the capsule 2 with different operating media depending on the type of surface treatment, which allows the production line to be used for different surface treatment methods without the need for structurally complex measures.

[0026] 2, the positioning frame 1 itself can be part of a connecting line 5, whereby a simple flow connection between the capsule 2 and the operating medium supply unit 6 is achieved. As a result of such measures, no connecting line 5 is exposed, which could impair an independent positioning, transport or approach of or to the capsule 2.

[0027] In order to allow a quick connection of the capsules 2 to the operating medium supply unit 6 and nevertheless a free movement of the capsules 2, the connecting line 5 is guided through the connecting element 3 and the positioning drive 4. The positioning drive 4, which serves in particular to transport the device stepwise over the production line, can be supported on rails 7.

[0028] When it is desired to supply the capsule 2 with several operating media simultaneously without impairing the free mobility of the capsule 2 or when it is desired to simultaneously influence process conditions, such as pressure, temperature and / or humidity, while supplying the operating media, the positioning frame 1 may have a connecting shaft 8 which mechanically connects the two connecting elements 3. In this case, the connecting shaft 8 forms two connecting pipe sections which are separated from each other by a check valve 9.

[0029] The connecting shaft 8 here serves as a horizontal axis of rotation, by means of which the capsule 2 can be rotated by means of a rotary drive 10 of the positioning drive 4. This allows any operating medium present to be distributed uniformly within the capsule interior, i.e. the reaction chamber, and thus to be applied uniformly to the workpieces (not shown).

[0030] To aid in the displacement of the device according to the invention along the production line, the positioning frame 1 may comprise a running platform 11 with rollers.

[0031] When the height H of the capsule upper part 12 exceeds the height h of the capsule lower part 13, the workpieces can be fed into the capsule 2 particularly easily.

[0032] In order to obtain a reliable electrical contact, despite the detachable connection between the capsule top 12 and the capsule bottom 13, without any possible cable wiring interfering with the free positioning of the capsule 2, the capsule top 12 and the capsule bottom 13 are connected to one another via a flange 14. For this purpose, the flange 14 has an electrical contact that is not shown.

[0033] For a reliable introduction or withdrawal of the operating medium into or from the capsule 2, the capsule upper part 12 has an inlet valve 15 connected to the connecting line 5, and the capsule lower part 13 has an outlet valve 16. In this embodiment, the check valve 9 therefore also assumes the function of the outlet valve 16. The positioning frame 1 together with the outlet valve 16 may pass through the capsule lower part 13.

[0034] 3 shows an emitter 17 which generates an alternating electromagnetic field, by which dielectrically or inductively excitable particles contained in the working medium, such as metal pigments in powder or liquid paints or possibly also nanoparticles, are excited and subsequently heated. The generated heat can be used to crosslink the working medium which is applied to the workpiece.

[0035] 4 illustrates the means for rotating the capsule 2 about a horizontal axis of rotation. The dashed lines 18 indicate the various filling levels of the operating medium when filling or discharging by the operating medium supply unit 6. This application relates to the invention described in the claims, but also includes the following as other aspects. 1. An apparatus for surface treating workpieces in a production line, comprising a positioning frame (1) for a workpiece to be treated, the positioning frame having a connecting member (3) for a positioning drive device (4), 1. An apparatus comprising: a positioning frame (1) on which a sealable capsule (2) is supported, the capsule (2) having connecting lines (5) for exchanging the operating medium with various operating medium supply units (6) arranged along the production line. 2. 2. The device according to claim 1, characterized in that the positioning frame (1) forms a connecting conduit (2) for flow connection to the capsule (2). 3. 3. The device according to claim 1 or 2, characterized in that the connecting pipe (5) is guided through a coupling member (3) to the positioning drive device (4). 4. 4. The device according to claim 3, characterized in that the connecting pipe (5) is guided through the positioning drive device (4). 5. 5. The device according to any one of claims 1 to 4, characterized in that the positioning frame (1) has a connecting shaft (8) connecting two connecting members (3) located opposite each other, the connecting shaft (8) forming two mutually separated connecting pipe sections for various operating media for both connecting members (3). 6. 6. The device according to any one of claims 1 to 5, characterized in that the connecting axis connecting the two connecting members (3) located opposite each other forms a rotation axis relative to the positioning frame (1) in order to evenly distribute the operating medium within the capsule (2). 7. 7. Any one of the above-mentioned devices 1 to 6, characterized in that the positioning frame (1) has a running platform (11) independent of the positioning drive device (4). 8. 8. Any one of the devices according to claims 1 to 7, characterized in that the height (H) of the capsule upper part (12) exceeds the height (h) of the capsule lower part (13) supported by the positioning frame (1). 9. 9. The device according to any one of claims 1 to 8, characterized in that the capsule upper part (12) is connectable to the capsule lower part (13) via a flange (14) extending around the capsule (2) and having an electrical contact. 10. 10. The device according to any one of claims 1 to 9, characterized in that the capsule upper part (12) has an inlet valve (15) for the operating medium, connected to the connecting line (5), and the capsule lower part (13) has an outlet valve (16) for the operating medium, connected to the connecting line (5). 11. 11. Any one of the devices according to claims 1 to 10, characterized in that the positioning frame (1) penetrates the lower part (13) of the capsule. 12. A method for surface treating a workpiece that is moved via a positioning frame (1) by a positioning drive device (4) in a production line, comprising: 1. A method according to claim 1, characterized in that the workpieces are placed in a sealable capsule (2) and then the closed capsule (2) supported on a positioning frame (1) is transported stepwise by a positioning drive (4) to various operating medium supply units (6) of the production line, where it is connected in each case, supplied with operating medium and separated again. 13. 13. The method according to claim 12, characterized in that the capsule (2) supplied with the operating medium is rotated about a horizontal axis of rotation. 14. 14. The method according to claim 12 or 13, characterized in that at least one operating medium has dielectrically or inductively excitable particles and the electromagnetically transparently configured capsule (2) is guided through an electromagnetic field to heat the particles.

Claims

1. An apparatus for surface treating workpieces in a production line, comprising a positioning frame (1) for a workpiece to be treated, the positioning frame having a connecting member (3) for a positioning drive (4), 1. An apparatus comprising: a positioning frame (1) on which a sealable capsule (2) is supported, the capsule (2) having connecting lines (5) for exchanging operating media with various operating medium supply units (6) arranged along the production line.

2. 2. Apparatus according to claim 1, characterized in that the positioning frame (1) forms a connecting line (5) connected to the capsule (2) for supplying the capsule (2) with operating medium.

3. 3. The device according to claim 1, wherein the connecting line (5) is guided through a coupling (3) to the positioning drive (4).

4. 4. The device according to claim 3, characterized in that the connecting line (5) is guided through the positioning drive (4).

5. 5. The device according to claim 1, wherein the positioning frame (1) has a connecting shaft (8) which connects two connecting elements (3) located opposite each other, the connecting shaft (8) forming two separate connecting pipe sections for different operating media for both connecting elements (3).

6. 6. The device according to claim 1, wherein the connecting axis connecting the two opposite connecting members (3) forms a rotation axis relative to the positioning frame (1) for uniform distribution of the operating medium in the capsule (2).

7. 7. Apparatus according to claim 1, characterized in that the positioning frame (1) has a running platform (11) independent of the positioning drive (4).

8. 8. The device according to claim 1, wherein the height (H) of the capsule upper part (12) exceeds the height (h) of the capsule lower part (13) supported on the positioning frame (1).

9. 9. The device according to claim 1, wherein the capsule upper part (12) is connectable to the capsule lower part (13) via a flange (14) which extends around the capsule (2) and has an electrical contact.

10. 10. The device according to claim 1, wherein the capsule upper part (12) has an inlet valve (15) for the operating medium, which is connected to the connecting line (5), and the capsule lower part (13) has an outlet valve (16) for the operating medium, which is connected to the connecting line (5).

11. 11. Device according to any one of the preceding claims, characterized in that the lower part (13) of the capsule is passed through by a positioning frame (1).

12. A method for surface treating a workpiece which is moved through a positioning frame (1) by a positioning drive device (4) in a production line, comprising:

1. A method according to claim 1, further comprising the steps of: placing a workpiece in a sealable capsule (2), after which the closed capsule (2) supported on a positioning frame (1) is transported stepwise by a positioning drive (4) to various operating medium supply units (6) of a production line, engaging each time, supplying the capsule (2) with operating medium and disengaging the capsule (2) again.

13. 13. A method according to claim 12, characterized in that the capsule (2) supplied with the operating medium is rotated about a horizontal rotation axis.

14. 14. The method according to claim 12 or 13, characterized in that at least one operating medium comprises dielectrically or inductively excitable particles and the electromagnetically transparently configured capsule (2) is guided through an electromagnetic field in order to heat the particles.

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