DE2016969A1 - Pickling process for obtaining perforations - in metallic sheet - Google Patents

Abstract

Process for obtaining perforations of desired shape with precision in which metallic sheet material is covered with a layer of pickle resistant material, which has been treated to give it the desired shape, on both sides and is then subjected to a light pickling treatment on one or both sides. A second pickle resistant film is then applied to one side of the sheet which has already been pickled and a second pickle is then carried out on the opposite side to form the desired perforations. The pickle resistant films are then removed. The process is carried out continuously.

Description

Method and apparatus for perforating metal parts The invention relates to a method and a device for perforating metal parts, in particular of thin metal plates, by means of chemical etching, in which one is against the etching medium Resistant stencil layer containing the perforation pattern to be produced is applied to both sides of the metal plates and the arrangement created in this way is subjected to chemical etching.

The technique of making shaped and shaped patterns Metal parts by means of the so-called photo-etching process, the photo-gra2 ^ ierprinzip Underlying is has been widely based on different in recent times technical fields have been applied. Among the items available on the market, that are generated by means of this technology are, for example, shadow masks.

for color television tubes, the most diverse metal screens, the leaves of shutter shutters, vacuum evaporator masks for the production of electronic Parts and many others.

In the manufacture of these articles by means of the etching technique mentioned If the thickness of the bare metal plate to be processed is relatively small, a stencil layer resistant to the etching medium with the desired pattern photographically printed on the plate and from a Side developed. However, the development is not limited to the photographic one Procedure. The chemical etching process is then carried out exclusively from the side made here, on which the stencil layer is located and thereby become the desired perforations worked out according to the template or to a certain extent "punched out". In many cases, however, the metal plate will also be on top of both of them Provide the pages with precisely aligned stencil layers and then the Etching process carried out simultaneously from both sides. This procedure is.; T Compared to the first mentioned, this is an advantage, since it creates perforations with higher. Maintain accuracy when the bare metal plates are of the same thickness. However, this method has also proven itself for the highest demands on accuracy the design has so far proven to be insufficient.

This is mainly due to the fact that during the etching process In chemical etching, the metal removal progresses only in a direction vertical to the bare surface is desired, in fact however, some side etch removal is inevitable. This causes however, a change in the composition and the temperature of the etching liquid as well as the composition of the material to be etched, resulting in an overall change the rate of removal and in particular in a lateral deformation and Deviation from the prescribed size and shape of the perforations results.

Especially in cases where the etching process is done simultaneously by both Side of the metal plate is carried out, the change in the removal rate makes itself doubly noticeable and results in a corresponding uselessness due to the poor shape accuracy. In the process in which the etching process is only carried out from one side, aas penetrates Etching medium until the end of the etching process, i.e. until the perforations are produced, in such a strong way Measure one side that matches the size of the perforations on the other width prove to be proportional to the thickness of the metal plate and thus an even more there is less accuracy of the manufactured product.

In the case of shadow masks for color television tubes, however, it is desirable that the perforations created by the etching process from one side to the other of the metal plate increase, i.e. in other words in one direction Side walls of the perforations are conical or wedge-shaped towards one another. In order to should be avoided that through the perforations to the fluorescent layer penetrating electron beams hit the side walls of the perforations and thereby either distracted or scattered.

The same applies to the opening grids for the so-called "Trinitron" picture tubes, although their shape differs from the usual shadow masks. To consciously To obtain perforations with this, Ke, il or cone shape, is so far with etching from both sides either the grid size of the printed stencils is different been chosen, or different amounts of etchant the two sides has been fed to the metal plate. This is done, for example, in that the spray pressure of the liquid from the nozzles has been kept different. It Both approaches have already been applied in one procedure.

Even in these cases where it is very much the exact The size of the smallest diameter of the perforations is important, despite the Measures used do not adhere to this size exactly, which leads to the double effect due to the different removal rates from both sides is. In addition, it differs from the production of conventional shadow masks with their independently formed perforations, it is the case with the "Trinitron" opening grilles it is absolutely important that in one precisely aligned in a predetermined direction and fine longitudinal strand braids lying parallel to one another are created.

It has been shown that in the known methods in which of is etched forth on both sides, the production of such opening grids is very difficult because the metal webs that remain between the longitudinal slots are already at The occurrence of low forces can break or twist. For example, this is enough the Druzl = forces when the etching liquid is sprayed on. Of course Grids damaged in this way are no longer suitable for practical use suitable.

Based on this prior art, it is the task of the present one Invention to propose a method and a device of the type described above, by means of which the described difficulties in etching from both sides can be eliminated and the production of perforations with considerably larger Allow accuracy and with significantly less risk of creating rejects. In particular, the process according to the invention for the production of the '"lirinitron" Opening grilles are suitable. According to the invention this object is achieved in that first is slightly pre-etched on at least one side of the metal plates, then one of the pre-etched sides completely covered and the opposite side etched and finally the stencil layer and the cover layer again be removed In an expedient embodiment of the method according to the invention will be the size of the perforations in the stencil layer on both sides of the Metal plate chosen differently. In a particularly advantageous development it is provided that the first pre-etching process is carried out from the side, on which there are the perforations in the stencil layer with the smaller dimensions are located.

The device for carrying out the method according to the invention is characterized by a first etching chamber containing the etching medium, a device for applying a cover layer to the plate, another etching chamber for receiving the plate provided with the cover layer and a transport device for conveyance of the plates between the individual treatment stations.

Further advantages and features of the present invention result from the following description of preferred house guide examples of the present Invention based on the accompanying drawings and the further subclaims.

There are shown: FIG. 1, 1A and FIG. 2, 2A, two different procedures according to the state of the art; Figure -3 and 3A to 3D successive process steps in the method according to the invention and FIG. 4, a schematic flow diagram based on a schematic representation of the etching device according to the invention, the inventive Process for perforating metal plates by means of chemical etching comprises im generally the following steps:. Application of a resistant to the etching medium Template layer, which has the desired shape, on both sides or Surface of a bare metal plate, carrying out a first light etch one or both sides of the metal plate, then applying one against the etching medium resistant cover layer over the entire surface of one of the only slightly etched sides or surfaces, of course with pre-etching only one side is covered, and then finish etching 'of the other side to get the desired Form perforations. Finally, the cover layer, which is resistant to the etching medium, is removed from the one Side and optionally the stencil layer from both sides of the metal plate removed.

The method according to the invention is explained in the following explanation -incoming step by step explained and thereby mit'den method according to the State of the art compared.

According to the known method in which etched from both sides is, as shown in Figures 1, lA, are first similar, resistant to etching, stencil layers 5a and 5b, precisely aligned with one another, applied to the opposite surfaces of a bare metal plate 6. This is usually done in such a way that first on both surfaces - a photosensitive Synthetic resin is applied, which hardens when exposed to light. For this purpose, e.g. the synthetic resin sold under the name KPR or TPR. Also one Photosensitive liquid, which also hardens upon exposure, can be used for which bichromate-containing glue or PVA is suitable. finally can also use a so-called positive-positive-light-sensitive liquid that becomes soluble on exposure. Subsequent to the application of one of these layers a negative plate with the desired pattern is placed tightly and the printing process by irradiating light from both sides by means of light sources of high intensity - Arc or mercury lamps - carried out. Then it is developed the layer hardened and fired.

In FIG. 1, the reference numeral 7 denotes the exposed metal surface areas denotes on which there is no stencil layer and which are etched should be removed. The prepared in this way, covered with the stencil layer Metal plate 6 is then opened from both sides at the same time bring me Etching liquid is flushed and thereby an even removal of the exposed Areas 7 caused by the etching of the medium used so that the Openings generated largely meet in the center plane of the metal plate 6. Thereupon the desired through openings 8 (FIG. 1A) are created. After attainment At this stage, the etching process is canceled and the stencil layers 5a, 5b are peeled off or rinsed off using a suitable fabric.

All chemicals that chemically use the Dissolve the metal used in the metal plate. The most common use is a aqueous ferric chloride solution for processing iron or copper plates.

As already mentioned, the removal process does not just take place in a direction normal to the surface of the metal plate, but also across it. As a result, each perforation 8 reduces inwardly towards itself, i.e. with in other words, the diameter greatest near the disk surface and is smallest in the area of the central plane 9 thereof.

However, the diameter changes due to the double effect the erosion from both sides with further progress. This results in, that due to the etching conditions a considerable change and deviation from the originally desired shape occurs.

FIG. 2 shows a further prior art procedure shown, also being etched from both sides. Here are the stencil images of the stencil layers 5a and 5b arranged on both sides in their size different, but with respect to the central axes of the openings to each other aligned. Such stencil layers can be easily made by known photography techniques produce.

The size of the exposed areas 1Oa and 1Ob, of which Metal is removed, thus differ from each other. So In the exemplary embodiment according to FIG. 2, each of the surface areas is ok the top of the plate smaller than the area 10b on the bottom.

Under this prerequisite, the process of blowing from both sides carried out ago, one obtains perforations 8, in which the smallest diameter 9 is near the top of the plate (Figure 2A). Also in this case doubled the effect of the lateral or transverse enlargement of the perforations due to the simultaneous etching effect from both sides, so that the size of the smallest 9-diameter range cannot be adhered to with certainty and precisely.

Notwithstanding the above known processes in the etching of The etching process according to the invention is carried out on both sides according to the schematic Representations in Figures 3 and 3A to 3D.

In the method according to the invention, it is also first on both Sides of the metal plate 6 (Figure 3) a stencil layer resistant to the etching medium 5a and applied, in the manner already described above in connection has been explained with FIGS. 1 and 2. Then from both sides a first slight pre-etching, preferably at the same time, carried out (Fig 3A). At this stage, however, it is not necessary from both sides to etch. The pre-etching process can also only be carried out from one side. In the latter case, it is preferred to etch from the side on which the exposed Surface areas (the top in Figure 3) are smaller as soon as these surface areas (10a and 10b) differ at all on both sides of the plate.

Then one will also be resistant to etching Cover layer 1i over the entire surface of one of the pre-etched pages applied when both sides had been pre-etched. If only one side was subjected to the pre-etching process, this is done by means of the cover layer 11 (Figure 3B) coated. Here, too, the cover layer is applied to the side, on which the exposed metal surface areas are smaller when they differ. The covering layer 11 thus removes the flat ones that have arisen from the pre-etching Recesses 12a covered. It is essential here that the recesses 12a (Figure 33) including its side walls actually completely through the Covering layer 11 are coated, so that they are in any case not subject to any etching effect can.

The second etching process is then carried out, which differs from the other side, which does not have a cover layer (FIG. 3B). This second etching process is continued until the recesses or perforations 12b reach the recesses 12a lying on the side of the cover layer 11. To After the 'production of the through perforations' takes place in this way, the cover layer is created 11 and the stencil layers 5a and 5b peeled off. The product presented here has perforations 13 with the desired training, the side walls in a Narrowing in the direction and its smallest diameter 9 near one side, as shown in Figure 3D.

The method according to the invention thus increases the accuracy with which can produce the smallest diameter 9 of each perforation 13, considerably increased, that is mainly due to the fact that even if it occurs less Variations in the rate of metal removal the side walls of the flat Recesses 12a, which have only been produced by the pre-etching process, one have gradients running almost perpendicular to the metal plate surface. There the etching process has been carried out only lightly, so that with caution Finish etching - with a slow removal rate - after the perforations have been formed with the desired design the size of the smallest diameter 9 remains practically unchanged. In this way you can find an article with the desired high accuracy.

The following is a device for carrying out the new etching process explained with reference to FIG.

As can be seen from the flow chart shown, is on far left end a web roll 15 or a replacement web roll 16 is arranged, on which a sheet of bare metal sheet is rolled up, which is already on both Sides the stencil layer, which is resistant to the etching medium, carries. These The layer is applied by means of known methods which are not discussed here been. The sheet metal web 17 is rolled off the roll by a suitable drive device 15 is withdrawn and runs through a connector 18 as well as a time equalization mechanism 19 into a pickling tank 20. The connecting device 18 and the time equalization mechanism 19 are designed so that the rear end of the sheet metal web, which is from the roller 15 expires, with the front end of the sheet metal web brought up from the exchange roller 16 can be connected to ensure a uniform etching process.

The pickling tank 20 contains any suitable pickling or cleaning liquid, which is agitated by means of a motor-driven agitator to produce a uniform etching effect to achieve.

After the pickling treatment, the sheet metal sheet is fed into a rinsing tank 21, where it is sprayed with water from spray nozzles and thereby freed from the pickling liquid The sheet metal web 17 then runs into a first etching chamber 22.

In the first etching chamber 22, groups of nozzles 23 are longitudinally opposite one another the path of the sheet metal path arranged, which eiten the etching liquid on both the sheet metal web 17 spray. The nozzle groups 23 can be perpendicular in a plane be pivoted or displaced for the forward movement of the sheet metal web 17 in order to thereby if necessary, the etching effect equalize. The etching liquid is supplied to the nozzle groups 23 from a corresponding supply source, wherein the etching liquid which is sprayed onto the sheet metal sheet 17 and then runs off again combined on the bottom of the chamber and the supply source for reuse is fed again.

In the roof of the etching chamber 22, a suction pipe 24 is provided from which the gases or vapors produced during the etching process can be discharged. The etching chamber 22 also contains suitably spaced apart Rollers 25 through which the sheet metal web 17 is guided as it passes through the chamber will.

In the first etching chamber 22, the sheet metal web 17 carried out only a slight etching and thereby the formation obtained in Figure 3A reached by perforations.

When the sheet metal sheet 17 with the pattern etched in this way, the chamber 22 leaves, it passes through air knife 26 at the outlet of the chamber through which the still existing excess etching liquid is removed. The sheet metal sheet treated in this way now arrives in a washing chamber 27. In the washing chamber 27, the web is first with it Sprayed water to remove any residual caustic liquid and its caustic effect, and then immersed in a wash tank 28. In addition, it will subsequently sprayed again to effectively and safely cleanse them of caustic to obtain. The cleaned sheet metal sheet 17 "arrives in a drying chamber 29, where it is dried in air and then enters a chamber 30, in to which a cover layer resisting the etching medium is applied.

In the chamber 30 there is a spray device 31, which is also in a plane vertical to the direction of movement of the sheet metal web 17, pivotable or displaceable is. This spraying device 31 sprays onto the side of the sheet metal sheet on which the Preetching has been carried out on an agent that is resistant to the etching medium is up the whole Area (see FIG. 3B) completely covered by it is. It is essential that the shallow recesses that go through the pre-etching process have been produced, are effectively completely covered around them To remove recesses of any etching effect in the subsequent etching steps.

The sheet metal is then turned into a. Drying chamber 32 with hot air works, guided and then enters a second etching chamber 33.

The second etching chamber 33 contains nozzle groups 34 for spraying Etching liquid, a suction tube 35 and support rollers 36, the total in arrangement and design correspond to those already contained in the first Etching Kanimer 22 are. The only difference between the two etching chambers is that the second etching chamber is generally longer than the first and that the nozzle groups 34 are only longitudinally are arranged on one side of the path. Of course this is the page which is opposite the side of the sheet metal sheet provided with the cover layer. Of the The etching process therefore only takes place from the uncovered side until the desired perforations in the sheet metal sheet 17 are made.

When leaving the second etching chamber 33, the sheet metal web arrives again between air knife 37, which removes any excess liquid from its surface remove. It is then fed into a washing chamber 38.

The washing chamber 38 is of the same design as the washing chamber 27 and contains water spray nozzles 39, a water tank 40 and other spray or Shower jets, three through which the sheet metal is also washed.

In a subsequent process step, the Ucilablonenschichten and stripping the cover layer from the sides of the sheet metal sheet. This is done using a suitable treatment fluid. The cutting of the sheet metal in. The desired Forming units or plates can either be carried out before or after the stripping process will.

In the embodiment described above, the first Etching treatment on both sides of the sheet metal. Is self-evident however, it is possible to carry out this etching treatment on one side only, i.e. on the side that will later be provided with the cover layer. In Figure 4 this is the top side of the sheet metal sheet.

That application of the cover layer can except by means of the one shown here Spray technology can be carried out by other known facilities. Also the transport device, which is used in the illustrated embodiment is not limited to the one shown in Figure 4, with the conveyor system in the horizontal direction, wherein the axes of the rollers are horizontal. It is also possible to use a vertical transport system ansuor, ¢ nen, in which the axis then e.g.

the web roll 15 is vertical.

In the device according to the invention is therefore first according to the corresponding Process on both sides of a metal web One stencil layer 5a, 5b each applied exactly aligned to each other and then the exposed surface areas1Oa, 10b of the web is subjected to a light etching process in the first etching chamber 22, see above that the flat recesses 12a, 12b form (Figure 3A).

Thereupon only one of the two sides of the sheet metal web is with a cover layer 11 is provided in the chamber 30 and in this way this side Protected against any etching effects. After that, it is not covered with the cover layer 11 provided side in the second etching chamber 33 subjected to the finishing etching process, by gradually deepening and widening the shallow recesses 12b until the Removal process the cover layer 11 over the flat recesses 12a on the opposite side (Figure 3C) reached. At this stage are the perforations 13th made in the metal track or metal plate.

As already explained above, the narrowest diameter can thus 9 of the perforations in the method according to the invention and by using the Manufacture device according to the invention with increased dimensional accuracy. Furthermore one obtains the second surface of the tetall sheet covered by the cover layer 11 aligned level with greater accuracy, since the cover layer 11 during the Etching process exerts a supporting effect. This even applies to the use of sheet metal thicknesses and materials subject to the impact or impact of the sprayed etching liquid or other occurring forces can only offer a low resistance, as is generally the case with the "Trinitron" opening grilles. Through the Cover layer 11 thus additionally increases the risk of breaking or twisting the remaining metal webs between the perforations during or after the Etching process reduced. It has been shown that even when using blank material, which tends to partially deform, often to warp, in the process according to the invention there is no risk of damage being caused by the procedure made possible manufacturing method with high functional reliability.

Claims (10)

Claims 1. Method for perforating metal parts, especially thin ones Metal plates, by means of chemical etching, in which a thin one against the etching medium Resistant stencil layer containing the perforation pattern to be produced is applied to both sides of the metal plates and the arrangement thus created is subjected to chemical etching, characterized in that first at least one side of the plates is lightly etched, then one of the slightly etched Sides completely covered and the opposite side is completely etched and finally the stencil layer and the cover layer are removed again 2. Method according to claim 1, characterized in that the size of the perforation openings Chosen differently in the stencil layers on both sides of the metal plate will. 3. The method according to claim 2, characterized in that the erote light etching process is carried out on the side on which the perforation openings are made with smaller dimensions. 4. The method according to any one of claims 1 to 3, characterized in that that the plates are treated in continuous tooth form. 5. Facility for carrying out the procedure according to the claims 1 to 4, characterized by a first etching chamber (22) containing the etching medium, a device (31) for applying a cover layer (11) to the plates (6, 17), another etching chamber (33) for receiving the one provided with the cover layer (11) Plates (6, 17) and a transport device for transporting the plates (6, 17) between the treatment stations. 6. Device according to claim 5, characterized in that spray nozzles (23) are arranged for spraying the etching liquid in the first etching chamber (22). 7. Device according to claim 6, characterized in that the spray nozzles (25) pivotable and / or displaceable perpendicular to the direction of movement of the plates (6, 17) are. 8. Device according to one of claims 5 to 7, characterized in that that the device for applying the cover layer (11) has a spray arrangement (31) is. 9. Device according to claim 8, characterized in that the spray arrangement (31) can be pivoted and / or displaced perpendicular to the direction of movement of the plates (6, 17) is. 10. Device according to one of claims 5 to 9, characterized in that that the second etching chamber (33) for applying the etching liquid also has spray nozzles (34) contains L e r s e i t e