EP0445120B1 - Device for applying and/or removing coatings on workpieces - Google Patents

Abstract

PCT No. PCT/DE89/00600 Sec. 371 Date May 24, 1991 Sec. 102(e) Date May 24, 1991 PCT Filed Sep. 22, 1989 PCT Pub. No. WO90/05801 PCT Pub. Date May 31, 1990.A device and method for using the device for applyng and/or removing coating on workpieces are disclosed. The device comprises a medium conveying device and a container adapted to receive the workpieces. The container has an inlet line connected to a medium source, an outlet line connecting the container to a medium source, the medium source being positioned below the conveying device, and a control device which connects the inlet and outlet lines to the medium source. The conveying device is a vacuum pump incorporated in the outlet line of the container.

Description

The invention relates to a device according to the preamble of claim 1.

In conventional devices of the type mentioned at the outset, such as e.g. are described in DE 10 34 447 B or GB 893 570 A, the medium is pressed into the process space, which has the consequence that when changing the medium, residual quantities are always deposited in the conveyor, which mix with the new medium. Thus, methods cannot be carried out with the known devices in which a high degree of purity of the medium to be conveyed into the process space is required. In addition, if the lines are damaged, the media are transported outdoors with high pressure, since there is overpressure in the lines and in the process room.

Based on the above prior art, the object of the invention is round, to further develop the generic devices without undue constructive effort so that they work without a deposit and in particular for one another. compatible liquids can be used.

The object is achieved according to the invention by the characterizing features of claim 1.

It can be seen that the invention is at least achieved when the circulation of the liquid, i.e. their movement from medium sources to the container (process space) and from there back to the medium sources takes place by means of negative pressure, so that there may be an implosion in the lines or the containers if leaks cannot be ruled out. In this case, the medium never flows outwards, but rather flows back alone and completely back into the associated meidum container. During operation there are no noticeable interruptions in operation, since the switchover can take place very quickly. Thus, one continuous cycle is replaced by the other continuous cycle, and in an extremely short time.

Further expedient and advantageous refinements of the invention emerge from the subclaims.

A particularly expedient measure of the invention provides that the conveying device is arranged above the medium source. The invention takes advantage of the fact that all lines located between the container (process space) and the medium containers as well as the control device, e.g. Radial or axial slides can be emptied without leaving any residue if there is no pressure in them and they are connected to the assigned medium containers to carry the medium.

A further expedient design of the invention provides that at least one opening for a holder carrying at least one workpiece is formed in the wall of the container (process space). It is particularly expedient here if the holder has an elastically deformable sealing section that is in pressure connection with the wall. In the context of this inventive concept, it is particularly advantageous if the Sheathing the opening is frustoconical and when it tapers inward.

Such a device can be used and used in particular in the medical and here in the dental field. The container (process room) consists of a material that is resistant to the media. Since there is negative pressure in the container (process space), the plugs in particular need not have a thread; rather, it is sufficient if they are inserted into the openings after they have been fitted with the workpieces. Due to the negative pressure, a force is exerted on the stoppers in the interior of the container, thereby preventing them from detaching from the container.

If the solenoid valve (V), which is located between the conveyor and the container (process room) and is used for venting, is then equalized, so that the liquid flows out of the container (process room) and the lines into the responsible medium container can, and that completely. The valve is opened to the outside regularly shortly before the end of an operation with a certain liquid. After that, when the valve is closed again, new and different liquid flows into the container (process space). After completing the entire process, the plugs can be removed from the openings. Of course, it is also possible to design the entire wall as a plate which can be detachably connected to the container (process space), which is equipped with the plugs and workpieces and then connected to the container (process space).

In a device for producing electrolytically producible coatings on metallic bodies, it is expedient if the surface of the sections of the projecting into the interior of the container (process space) Workpieces are designed as cathodes or anodes if an anode or cathode is arranged opposite the workpieces and if an electrolyte flows between the electrodes. In order to ensure that the inflowing liquid also rinses the workpieces sufficiently, it is expedient if a device influencing the flow direction of the liquid is arranged within the container (process space). If this is a device in which the incoming line in the bottom area and the outgoing line in the upper area of the container (process room) can be connected, then it is advantageous if the device consists of two at a distance from the floor or ceiling of the container (Process room) arranged plates which cover the floor or the ceiling except for a gap or slot in the wall area of the wall carrying the workpieces. This ensures that the inflowing liquid flows along the inside of the wall carrying the workpieces and optimally rinses the workpieces.

In the case of a device which can be connected to an electrolyte and a pre-rinse and a rinse water tank, it is advantageous if an ion exchanger for regeneration of the rinse water is arranged in the pre-rinse and rinse water tanks. It is particularly expedient here if two ion exchangers are arranged in each container. Such an ion exchanger can consist of a hollow body which can be detachably connected to the inlet or outlet opening of the container and has an inlet and an outlet opening, means for receiving ions being arranged between these openings. The advantage of these measures is that the ion exchangers - they no longer fulfill their function - come from the container can be removed and replaced with new ones. The operator of the device does not come into contact with any liquid.

The invention also relates to a method for applying and / or removing coatings on workpieces by means of a device according to the above measures. The procedure here is that the workpieces are arranged in the interior of the container (process space), that the workpieces are then, if necessary, pretreated so that the control device is actuated so that the container (process space) is covered by an electrolyte or another chemical liquid is flowed through, and that after formation of a certain coating layer, the control device connects the lines to a rinsing liquid, which is then transported through the container (process space).

• Fig. 1 eine Vorrichtung zum Galvanisieren,
• Fig. 2 einen Behälter (Prozeßraum), vergrößert dargestellt,
• Fig. 3 einen Behälter für eine Mediumquelle, vergrößert dargestellt,
• Fig. 4 einen Behälter (Prozeßraum) mit einer außerhalb des Behälters angeordneten Anode,
• Fig. 5 eine räumliche Anordnung einer Anode mit Bezug auf ein Werkstück und
• Fig. 6 einen weiteren Behälter für eine Medienquelle.

Some embodiments of the invention are shown schematically in the drawing and are explained in more detail below. Show it:

• 1 shows a device for electroplating,
• 2 a container (process room), shown enlarged,
• 3 shows a container for a medium source, shown enlarged,
• 4 shows a container (process space) with an anode arranged outside the container,
• Fig. 5 shows a spatial arrangement of an anode with respect to a workpiece and
• Fig. 6 shows another container for a media source.

In Fig. 1 is a device for applying and / or removing coatings on workpieces 10 and 12 with a workpiece 10 and 12 receiving container (process space) 14 with an incoming, connectable to at least one medium source 18 and an outgoing, the container (Process room) 14 with the medium sources 18, 19 and 21 of connectable lines 16 and 20, the connection between the lines 16 and 20 and the medium sources 18, 19 and 21 being effected by means of a control device 24, here radial slide valve.

The control device 24 is a valve which consists of two circular disks 1 and 2, which can be rotated relative to one another about a common axis, on the one hand below the container (process space) 14 and on the other hand above the medium sources 18, 19 and 21 is arranged, the lines 18 and 20 are essentially vertical so that no depots are formed in them. By means of the radial slide 24, the lines 16 and 20 can be connected to more than two containers 18, 19 and 21. A vacuum delivery device 26 is connected in the outgoing line 20, in the present exemplary embodiment a vacuum pump. The liquid is therefore e.g. conveyed from the container 18 into the line 16 and from there into the container (process space) 14. Since there is negative pressure in the container (process space) 14, the liquid flows via the line 20 into the radial slide valve 24 and from there back into the container 18.

Fig. 1 also shows that in the wall 28 of the container (process room) 14 two openings 30 and 32 for the Workpieces 10 and 12 supporting brackets 40 and 42 are formed. The brackets 40 and 42 have an elastically deformable sealing section which is in pressure connection with the wall 28. The casing of the openings 30 and 32 is frustoconical and tapers inwards. If the device shown in FIG. 1 is now to be used for producing electrolytically producible coatings on metallic bodies, then the surface of the section of the workpieces 10 and 12 protruding into the interior of the container (process space) 14 is designed as a cathode or anode, while opposite the workpieces 10 and 12 an anode 44 or cathode is arranged. The liquid flows between these electrodes.

In order to ensure that the liquid supplied through the line 16 acts on the workpieces 10 and 12, a device 50 and 52 influencing the flow direction of the liquid 46 is arranged inside the container (process space) 14. The incoming line 16 is in the bottom area, which can preferably be funnel-shaped, and the outgoing line 20 is connected in the top area of the container (process space) 14. The device 50 and 52 influencing the liquid flow consists of two plates which are arranged at a distance from the floor 54 or the ceiling 56 of the container (process space) 14 and which cover the floor 54 or the ceiling 56 apart from a gap 60 and 62 in the wall area of the cover the workpieces 10 and 12 supporting wall 28.

Fig. 1 also shows a valve (V) which is connected in the line 20 and between the conveyor 26 and the container (process room). The valve (V) designed as a solenoid valve for ventilation is always then actuated when the container (process space) 14 is emptied and the medium located there is to get into the responsible medium container 18, 19 and 21. In this case, a pressure equalization takes place in the container (process space) 14, so that the liquid can flow down via the line 16. The conveyor 26 does not have to be switched off.

2 shows that the workpieces 10 and 12 can be acted upon by the inflowing electrolyte also by means of a swirling device, propeller 3, arranged inside the container (process space) 14.

1 in connection with FIG. 3 shows particularly well that two ion exchangers 64 and 66 are arranged in the rinsing water container 19 for the regeneration of the rinsing water. The ion exchangers 64 and 66 each consist of a hollow body which can be detachably connected to the inlet or outlet opening 70 or 72 of the container (process space) 14 and which has an inlet and an outlet opening 74, 78 or 76 and 80. Between these openings are means 82, here resin, arranged to receive ions.

If an ion-containing liquid, for example water, now flows into the container 14 through the line 6, it arrives in a hollow body 90 of the ion exchanger 66. This hollow cylindrical hollow body 90 has a multiplicity of radially aligned openings 91 and 92 outflowing liquid is pressed by the ion receiving means 82 and passes through the opening 76 into the interior of the container (process space) 14. The liquid flowing out of the opening 76 into the interior is essentially free of cathions or anions. From there, the liquid reaches the opening 78 Interior of the second ion exchanger 64, which is essentially constructed in exactly the same way as the first ion exchanger 66, but which catches cathions or anions. The liquid flowing out of line 7 is thus freed of ions. If the ion exchangers 64 and 66 are inoperative, they are removed from the container 14 and replaced by others.

The wall 28 of the container 14 can also be designed as a blank magazine.

The particular advantage of the invention is therefore that not only large systems such as pipes with a length of several meters can be coated in the same way, but also small objects such as screws, rings or dental prostheses. In order to avoid the oxidation of the coating, the electrolyte can e.g. be mixed with nitrogen. The electrolyte can e.g. can be swirled by stirring or ultrasound. It has been shown to be particularly expedient to use insoluble anodes or electrodes here. It is also ensured that no evaporation losses of the liquids occur.

If galvanic coatings are to be produced on workpieces with an uneven surface, the distance between the anode and the cathode (workpieces) has a decisive influence on the thickness of the coating layer. The thickness depends on the current density and the exposure time. Because of the different currents at the edges, recesses and indentations in the workpieces, the layer thickness is not quite uniform. This results from the fact that the recesses are at a greater distance from the anode than the end face of the workpiece facing the anode.

This can be remedied in part by removing the anode from the workpieces to such an extent that the depth of the recesses is vanishingly small with respect to the distance of the anode from the cathode. However, this has the disadvantage that the container must be built significantly larger regularly.

annähernd = 1. Die Stromstärke ist im Bodenbereich 116 annähernd gleich groß wie im Stirnbereich 115, so daß die Dicke des Überzuges annähernd gleich ist.4 and 5 show that the length of the field lines 110 and 111 is very long, although the distance between the anode 104 and the workpieces 10 and 12 is relatively small. The anode 104 is accommodated in a receptacle 100, whose distance from the workpiece 10 is significantly less than the length of the field lines 110 and 111 between the anode 104 and the cathode 10. The receptacle 100 is outside the container (process space) 14 arranged. This is a stretched body, the open side 120 of which communicates with the container (process space) 14. A number of baffles 106 and 107 are arranged between the open side 120 and the anode 104. The baffles 106 and 107 are designed as guide plates, so that the field lines 110 and 111 are serpentine and serpentine. As a result, the length of the field lines - measured from the anode 104 to the workpiece 10 - is increased so that the bottom side 116, which is an amount x further away from the anode, is approximately as far away from the anode as the end face 115 of the workpiece 10. If the length of the field lines d is referred to, ie the length of the field line 110 from the anode to the end face 115, and the distance of the field line 110 'is d + x, then

approximately = 1. The current strength in the bottom region 116 is approximately the same as in the front region 115, so that the thickness of the coating is approximately the same.

In order to focus the streamlines 110 and 111, apertures 108 and 109 are also provided, by means of which it is intended that the streamlines 110 and 111 leave the outlet 120 with approximately the same density.

5 also shows that the anode 104 is surrounded by granular particles 121, which may consist of copper, nickel, gold, silver, chromium or the like. The particles 121 are accommodated in a collecting container 102, which communicates with the receiving container 100. The receptacle 100 and the collecting container 102 are formed in one piece and are essentially L-shaped, the lower end of the collecting container 102 surrounding the anode. Galvanic coatings are produced by electrolytic decomposition of metal salt solutions. A copper coating on the metal article 10 can be made by hanging the article as a cathode in a copper sulfate solution and using an anode made of circuit board as the anode, which is made of copper particles, e.g. Granules, small balls, etc., surrounds. The Cu⁺⁺ ions go to the negatively charged object and form the coating there, while the residual acid ions SO₄⁻⁻ release new Cu⁺⁺ ions from the Cu anode, so that the concentration of the solution is maintained. The current density must be kept sufficiently low, otherwise the Cu coating becomes porous and spongy. The result of the granules is that the distance of the anode 104 from the workpiece 10 is kept constant, since the used granules arranged in the bottom area of the anode 104 can be replaced by new granules which extend to the cover 103.

Finally, FIG. 6 shows a container 200 which corresponds approximately to the medium container 19 according to FIG. 1. The main difference between the container 200 and the Medium container 19 consists in that the complete container 200 is designed as an ion exchanger which can be connected to the lines 16 and 20 via the radial slide 24 by means of connections 212 and 214. The container (ion exchanger) 200 has three filters 202, 204 and 206, between which ion receiving means for cations 208 and anions 210 are arranged, for example in the form of resin. This ion exchanger 200 can be operated in both directions.

Claims (21)

1. Device for applying and/or removing coatings on workpieces, having a conveying device and a container (process chamber) receiving the workpieces, with an inlet line which is connectable to medium sources and an outlet line which can connect the container (process chamber) with the medium sources disposed below the conveying device, wherein the connection between the lines and the medium sources is established by means of at least one control device which is connectable to at least three different medium sources and disposed below the container (process chamber), characterised in that the conveying device (26) is a vacuum pump and incorporated in the outlet line (20) of the container (process chamber) (14).
2. Device according to claim 1, characterised in that the inlet line (16) terminates in the area of the lowest point of the container (14).
3. Device according to claim 1 or 2, characterised in that the media continuously circulate in closed cycles.
4. Device according to one of claims 1 to 3, characterised in that a valve (V), in particular a magnetic valve, is incorporated in the outlet line (20) and between the conveying device (26) and the container (14).
5. Device according to one of claims to 4, characterised in that means (3) are provided, by which the medium present in the container (process chamber) (14) can be swirled.
6. Device according to one of claims 1 to 5, characterised in that at least one opening (30,32) for a holder (40,42) supporting at least one workpiece (10,12) is formed in the wall (28) of the container (process chamber) (14).
7. Device according to one of claims 1 to 6, characterised in that the holder (40,42) has an elastically deformable sealing section connected under pressure with the wall (28).
8. Device according to one of claims 1 to 7, characterised in that the sheathing of the opening (30,32) is in the shape of a truncated cone, and in that it tapers towards the interior.
9. Device according to one of claims 1 to 8 for manufacturing electrolytically producible coatings on metallic bodies, characterised in that the surface of the sections of the workpieces (10,12) extending into the interior of the container (process chamber) (14) is designed as a cathode or anode, in that an anode (44) or a cathode is disposed opposite the workpieces (10,12), and in that an electrolyte (46) flows between the electrodes.
10. Device according to one of claims 1 to 9, which can be connected to an electrolyte reservoir (18) and a pre-rinse and rinse water reservoir, characterised in that at least one ion exchanger (64,66) for the regeneration of the rinse water is disposed in the prerinse and rinse water reservoir (19).
11. Device according to claim 10, characterised in that two ion exchangers (64,66) each are disposed in each reservoir (19).
12. Device according to claim 9 or 11, characterised in that the ion exchanger (64,66) consists of a hollow body, which is removably connectable with the inlet or outlet opening (70,72) of the container (process chamber) (14) and has an inlet and outlet opening (74, 78; 76, 80), and in that means (82) for absorbing ions are disposed between these openings.
13. Device according to one of claims 1 to 12, characterised in that the temperature of the liquids contained in the reservoirs is maintained at a set value (0°C).
14. Device according to one of claims 1 to 13, characterised in that the anode (104) or cathode is housed in a receptacle (100), the distance of which from the workpiece (10) is clearly less than the length of the lines of electrical flux (110,111) between the anode (104) and the cathode.
15. Device according to one of claims 1 to 14, characterised in that the receptacle (100) is disposed outside of the container (process chamber) (14).
16. Device according to one of claims 1 to 15, characterised in that the receptacle (100) is a stretched body, the open side (120) of which communicates with the container (process chamber) (14), and in that baffles (106,107) are formed between the side (120) and the anode (104).
17. Device according to one of claims 1 to 16, wherein the container is circular or rectangular in cross-section, characterised in that the baffles (106,107) are in the form of guide plates, so that the lines of electrical flux (110,111) are serpentine.
18. Device according to one of claims 1 to 17, characterised in that the anode (104) is surrounded by granulate-shaped particles (121) of Cu, Ni, Au, Ag, Cr, Sn or the like.
19. Device according to one of claims 1 to 18, characterised in that the particles (121) are housed in a collector (102) which communicates with the receptacle (100).
20. Device according to one of claims 1 to 19, characterised in that the receptacle (100) and the collector (102) are made of one piece and are essentially L-shaped, wherein the lower end of the collector (102) surrounds the anode.
21. Method for applying and/or removing coatings on workpieces by means of a device according to one of claims 1 to 20, characterised in that the workpieces are disposed in the inner chamber of the container (process chamber) (14), in that subsequently the workpieces (10,12) are pre-treated, if necessary, in that the control device is actuated, so that an electrolyte or other chemical liquid flows through the container (process chamber), and in that, after a set coating layer has been formed, the control device connects the lines to a rinsing liquid, which is then moved through the container (process chamber).

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