Device for holding workpieces during electrolytic treatment

Abstract

The present invention relates to a device for holding a workpiece during an electrolytic treatment, in particular a device for holding a workpiece during an electrolytic treatment in at least one container having an anodizing bath and / or a coating bath, the device comprising at least one or more liftable frame columns, the frame columns having support arms which are arranged in pairs in height on the frame columns, between which the workpiece can be clamped respectively, and wherein power is supplied to the workpiece via the frame columns and the support arms, wherein the first support arm of each support arm pair has a bent section or a formed part, by means of which the edge of the workpiece can be fixed by overlapping, and the second support arm has an inner jaw side and an outer jaw side in a jaw-shaped manner and is constructed in a curved manner pointing in the direction of the first support arm for accommodating the other edge of the workpiece, and the jaw opening is designed so that the inner jaw side exerts pressure on the workpiece when the workpiece is clamped between the support arms.

Description

Technical Field

[0001] The invention relates to a device for anodizing, in particular metal workpieces, and / or for coating in a container, wherein the workpieces are suspended on a support frame and are lowered into a corresponding bath. Background Art

[0002] Such devices are known. In the simplest case, according to DE 94 11 523 U1, the object to be treated or the workpiece to be treated is clamped on a support frame, for example, by means of clamping arms or calipers to clamp an aluminum rail. The support frame with the clamping arms and the workpiece is then lowered into an anodizing tank with an electrolyte. One or more cathodes are also arranged in the anodizing tank, so that a closed current circuit can be formed via the workpiece and the electrolyte.

[0003] This has the disadvantage that during the anodizing process, a layer which is no longer electrically conductive, for example an oxide layer, forms on the support frame and the clamping arms or calipers. The frame must therefore be pickled regularly. This is not only technically disadvantageous, but also leads to environmental problems with regard to the disposal of the chemicals used for pickling. As an alternative to support frames with clamping arms or calipers made of aluminum, such support frames made of titanium or titanium alloys have been provided, since this material has a high degree of chemical resistance.

[0004] A disadvantage here is also the poor electrical conductivity (15 times lower than that of aluminum), so that titanium anodes have hitherto been used only in the case of smaller aluminum components. A further disadvantage is that contact bridges are formed in an uncontrolled manner, which leads to blackening in the aluminum material to be treated. The contact current is susceptible to fluctuations, so that the layer thickness of the layer produced by the anodizing process cannot be precisely defined.

[0005] In the device according to DE 101 45 554 C1, very thin and flat objects to be treated are used. In order to transport a large number of objects to be treated simultaneously to the electrochemical treatment facility, these objects to be treated are suspended and clamped on a stacking hanger. The clamping is achieved by a clamping piece with a clamping device. Due to the assembly cost, this type of suspension is very expensive.

[0006] According to DE 85 02 551 U, a contact pliers for electrophoretic painting of metal parts is proposed. Screw clamps, bent lever pliers or articulated leg pliers loaded with helical compression springs are already known. However, their movable parts are quickly clogged with paint and are also complicated to construct. Therefore, a contact pliers with two pliers legs is proposed, which are elastically connected by a U-shaped leaf spring. A conductor strip is fastened on one pliers leg between the inner side of the pliers leg and the leaf spring. The conductor strip can be connected to a connecting cable at the other end. The contact pliers have only a small clamping area and a low extrusion force and are therefore only suitable for small workpieces.

[0007] According to the applicant's EP 1 889 951 B1, a device and a method for electrochemically treating thin objects to be treated are proposed, which no longer require continuous cleaning of the support frame and the fixture, and enable better transmission of current from the fixture to the workpiece. For this purpose, the calipers of the fixture are made of titanium and are designed with ridges on the surface. In addition, intermediate pieces made of aluminum are arranged between the workpiece and the calipers, which form wear parts and improve current transmission.

[0008] According to DE 12 41 887 B, a device for establishing an electrical connection between a product carrier unit and the edge of a container of an electroplating facility is proposed. As a prior art, a product carrier unit is described with a wedge-shaped track for placement on the edge of the container, which is embedded in a V-shaped contact body on the container. As a further variant, a knife-type contact between the contact metal ferrules is described. However, these variants do not allow sufficient current to flow in the case of large workpieces. In order to improve the current transmission, it is proposed to arrange a spring-loaded wedge on the side of the contact rail in order to increase the surface pressure.

[0009] This solution for generating sufficient contact pressure is relatively expensive and requires frequent maintenance. This variant is not very suitable for producing electrical connections between a large number of workpieces and product carriers, because the contact area is lowered into the immersion bath liquid. Here, this part of the device is also exposed to the electroplating process and must be cleaned after each immersion bath. Summary of the invention

[0010] The object of the present invention is to propose a support frame in a device for electrolytic treatment of metal workpieces in a container with an anodizing bath or a coating bath, which support frame has support arms for the workpieces, by means of which a safe, quickly fixable and removable connection to the workpieces can be achieved and at the same time a defined and safe current transmission from the support arms to the workpieces is ensured.

[0011] This object is achieved with the features of claim 1. Advantageous embodiments are the subject matter of the dependent claims.

[0012] In a device for holding a workpiece during an electrolytic treatment in at least one container having an anodizing bath or a coating bath, the device has at least one or more liftable frame columns, the frame columns having support arms arranged in pairs on the frame columns in height, between which the workpiece can be clamped, and wherein power is supplied to the workpiece via the frame columns and the support arms, according to the invention, the first support arm of each support arm pair has a bent section or a formed part, by means of which the edge of the workpiece can be fixed by overlapping, and the second support arm has a jaw-shaped inner jaw side and an outer jaw side and is bent in a manner pointing in the direction of the first support arm. The support arms are configured to accommodate an additional edge of a workpiece, and the jaw opening is designed so that the inner jaw sides exert pressure on the workpiece when the workpiece is clamped between the support arms.

[0013] In this embodiment, current is thus additionally supplied via the inner jaw side, which preferably provides a current of 3 to 8 kg / mm 2 , preferably 5kg / mm 2 The contact pressure of the left and right sides is reduced, thereby hindering the oxidation of the contact surface (line or point). In such an embodiment, it has been proven to be useful that the support arm, the bent section, the formed part and the jaw side are made of titanium for anodizing or coating.

[0014] In order to prevent oxidation of the rough titanium surface, one embodiment provides that the frame struts, the support arms, the angled sections, the formed parts and the jaw sides have a PVC coating, at least with the exception of the contact points with the workpiece.

[0015] It is more advantageous to implement a PFA coating (perfluoroalkoxy polymer) due to the higher temperature resistance of 240° C., at least except for the contact points with the workpiece. The higher temperature resistance allows for method steps such as blackening at 230° C., for example, without having to replace the workpiece carrier, which significantly increases the productivity of the system.

[0016] In a preferred embodiment, the inner jaw side extends beyond the outer jaw side, wherein the inner jaw side points toward the jaw opening at an obtuse angle α.

[0017] In order to achieve an optimal spring action of the support arms when clamping the workpiece, the first support arm is designed to be longer than the second support arm, for which purpose the first support arm is designed to be arched and / or bent or has a spiral section. In this way, despite the different spring elasticities of the support arms, the spatial extension of the frame support and the workpiece can be limited.

[0018] In this sense, it is effective that the fastening of the first support arm to the frame strut is arranged on the side of the frame strut facing away from the workpiece to be received by the support arm. Preferably, the support arm has a circular cross section, which in the region of the contact point with the workpiece has a flat surface or changes into a rectangular cross section, so that the contact point runs linearly. If the number of contacts for the current to be transmitted in the cross section is sufficient, the contact point can also be designed in a punctiform manner.

[0019] Furthermore, the shaped part has a cutout, preferably a V-shaped or trapezoidal recess, for receiving the edge of the workpiece. However, it is also possible that the shaped part is matched to the fastening point on the workpiece.

[0020] The pairs of support arms are arranged opposite each other on the frame struts, wherein the frame struts can be spaced apart from each other by means of a frame and can be positioned next to each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention is described with reference to the accompanying drawings, in which:

[0022] Figure 1 A frame support column with a workpiece is shown;

[0023] Figure 2 The arrangement of the support arms formed in the shape of a jaw is shown;

[0024] Figure 3 A support arm is shown in the shape of a jaw; and

[0025] Figure 4 A support arm with a formed part is shown. DETAILED DESCRIPTION

[0026] Figure 1 A device for holding workpieces during electrolytic treatment in a vessel with an anodizing bath and / or a coating bath is shown, which has a liftable frame column 1. Support arms 3, 4 are arranged in pairs at a height opposite to each other on the frame column 1, between which a workpiece 9 can be clamped. Here, the workpiece 9 is shown in the form of a roof rack of a passenger vehicle.

[0027] The lower support arm 3 of each support arm pair is of arcuate and angled design and has a formed part 5 at the end facing away from the frame strut 1 , by means of which the edge of a workpiece 9 can be fixed.

[0028] The upper second support arm 4 has a jaw-like shape with an inner jaw side 7 and an outer jaw side 6 and is designed in a curved manner pointing in the direction of the first support arm 3 for accommodating a further edge of the workpiece 9, wherein the jaw opening is designed so that the inner jaw side 7 exerts pressure on the workpiece 9 when the workpiece 9 is clamped between the support arms 3, 4.

[0029] The support arms 3, 4, the angled sections, the shaped part 5 and the jaw sides 6, 7 are made of titanium for anodizing or for coating and have a PFA coating (perfluoroalkoxy polymer) in order to smooth the rough titanium surface, at least with the exception of the contact points with the workpiece 9. The use of titanium has the advantage that the spring stability of the support arms 3, 4 is maintained for a significantly longer period of time, for example, compared to aluminum.

[0030] from Figure 1 As can be seen in the figure, the lower support arm 3 has a longer length than the upper second support arm 4, for which reason the lower support arm is designed in an arched and bent manner. In addition, the fastening of the lower support arm 3 to the frame column 1 is arranged on the side of the frame column 1 that is opposite to the workpiece 9 to be accommodated by the support arm 3.

[0031] In this way, different spring rates can be achieved between the support arms without a greater spatial extension, i.e. the lower support arm 3 is more elastic or only elastic, while the upper support arm 4 is essentially rigid. In this way, the edge pressure can be set relatively accurately at 3 to 8 kg / mm 2 Between, preferably 5kg / mm 2 This hinders oxidation and thus discontinuous current delivery.

[0032] In this embodiment of the support arms 3 , 4 , the current supply to the workpiece 9 is additionally achieved by the jaw-like design of the support arm 4 .

[0033] If the workpiece 9 is hung in the jaws of the support arm 4 and moved in the direction of the frame column 1 until the connection to the workpiece 9 is also established via the support arm 3, the workpiece 9 is pressed against the jaw sides 6, 7, wherein the inner jaw side 7 is pressed against the workpiece 9 due to its length and the obtuse angle α.

[0034] The geometry of the jaw sides 6, 7 is designed in such a way that the pressure acting on the workpiece 9 is between 3 and 8 kg / mm. 2 Between, preferably 5kg / mm 2 .

[0035] The support arms 3, 4 preferably have a circular cross section which has a flat surface in the region of the contact point with the workpiece 9, or transforms into a rectangular cross section so that the contact point extends linearly, wherein point contacts are sufficient if the number of contacts for the current to be transmitted in the cross section is sufficient.

[0036] Figure 2 The functioning of the upper support arm 4 with the jaw-like opening is shown in an enlarged view.

[0037] The support arm 4 overlaps the edge of the workpiece 9 with the bent outer jaw side 6, here the inner profile edge, so that the edge of the workpiece 9 is located between the two jaw sides 6, 7. Since the inner jaw side 7 is longer and points at an obtuse angle α to the jaw opening, the movement of the workpiece 9 in the direction of the frame support 1 leads to a pressure buildup between the jaw side 7 and the workpiece 9, while the jaw side 6 serves as a support or counter-support.

[0038] Like the support arm 3 , the support arm 4 is preferably arranged in the receptacle 2 of the frame strut 1 .

[0039] Figure 3 Only the support arm 4 with the jaw sides 6, 7 is shown.

[0040] Figure 4 The lower support arm 3 is shown, which, due to its arcuate and angled shape, has a longer length than the support arm 4 and thus has a greater spring elasticity.

[0041] Reference numerals list

[0042] 1 Frame support

[0043] 2 Receptacle for support arm on frame support

[0044] 3 First support arm

[0045] 4 Second support arm

[0046] 5 Formed parts

[0047] 6 Outer jaw side

[0048] 7 Inner jaw side

[0049] 8 V-shaped or trapezoidal concave part of the formed part

[0050] 9 Workpiece

Claims

1. A device for holding workpieces during electrolytic treatment in at least one container having an anodizing bath and / or a coating bath, the device comprising at least one or more liftable frame columns (1), the frame columns having support arms (3, 4) arranged in pairs in height on the frame columns (1), between which workpieces (9) can be clamped, and wherein: The workpiece (9) is powered via the frame support (1) and the support arms (3, 4), characterized in that: The first support arm (3) of each support arm pair has a bent section or a shaped part (5), by means of which the edge of the workpiece (9) can be fixed by overlapping. The second support arm (4) is jaw-shaped and has an inner jaw side (7) and an outer jaw side (6) and is configured in a curved manner so as to point in the direction of the first support arm (3) for accommodating a further edge of the workpiece (9), and the jaw opening is designed so that the inner jaw side (7) exerts pressure on the workpiece (9) when the workpiece (9) is clamped between the support arms (3, 4).

2. The device according to claim 1, characterized in that The support arms (3, 4), the bent sections, the shaped part (5) and the jaw sides (6, 7) are made of titanium for anodizing or painting.

3. The device according to claim 1 or 2, characterized in that For anodizing, the frame struts (1), the support arms (3, 4), the angled sections, the shaped parts (5) and the jaw sides (6, 7) are provided with a PVC coating, at least with the exception of the contact points with the workpiece (9).

4. The device according to claim 1 or 2, characterized in that The frame struts (1), the support arms (3, 4), the angled sections, the shaped parts (5) and the jaw sides (6, 7) have a PFA coating, at least with the exception of the contact points with the workpiece (9).

5. The device according to claim 1 or 2, characterized in that The inner jaw side (7) extends beyond the outer jaw side (6), and the inner jaw side (7) points toward the jaw opening at an obtuse angle α.

6. The device according to claim 1 or 2, characterized in that The contact pressure between the inner jaw side (7) and the workpiece (9) is between 3 and 8 kg / mm 2 between.

7. The device according to claim 1 or 2, characterized in that The contact pressure between the inner jaw side (7) and the workpiece (9) is 5 kg / mm 2 .

8. The device according to claim 1 or 2, characterized in that The first support arm (3) is longer than the second support arm (4), for which purpose the first support arm is designed in an arcuate and / or bent manner or has a spiral section.

9. The device according to claim 8, characterized in that The fastening portion of the first support arm (3) on the frame column (1) is arranged on a side of the frame column (1) facing away from a workpiece (9) to be received by the support arm (3).

10. The device according to claim 1 or 2, characterized in that The support arms (3, 4) have a circular cross section which, in the region of the contact point with the workpiece (9), has a flat surface or transitions into a rectangular cross section.

11. The device according to claim 1 or 2, characterized in that The shaped part (5) has a cutout for accommodating an edge of the workpiece (9).

12. The device according to claim 11, characterized in that The cutout is a V-shaped or prism-shaped recess.

13. The device according to claim 1 or 2, characterized in that Pairs of support arms (3, 4) are arranged opposite to each other on the frame support (1).

14. The device according to claim 1 or 2, characterized in that The frame struts (1) are spaced apart from each other by the frame and positioned side by side.

Images