DE2101332A1 - Electroplating Drum and Process - Google Patents

Description

HANSHENIG »nOrnberc

PARSIFALSTITAtSI 6 TEL. 46 »7 79

Electroplating Drum and Process

The invention relates to a drum for electroplating pourable Mass parts made of plastics or metals, if necessary also for pickling and electroless plating of pourable Bulk parts made of plastics or for anoic polishing of bulk metal parts, completely or almost completely immersed in the electrolyte, mainly from a pair of spaced apart, preferably vertical to the axis of rotation of said drum arranged end faces and from one, fixed between said end faces peripheral, prismatic or cylindrical jacket consisting of said end faces and said jacket existing housing of the drum on its peripheral circumference with at least one, for loading or unloading the ones to be electroplated Serving mass parts and during electroplating with a lid to be closed opening is provided. The electroplating of bulk parts made of plastics or metals in bell-shaped or drum-shaped containers is used in industry - for reasons of economy - an ever wider one Use. The type of treatment enables the bulk parts to be filled in batches into the individual containers, which are in Immerse various types of alkaline or acidic treatment solutions (electrolytes) and rotate in them. The surface of the Plastic mask parts are made - before the start of the electroplating process - Generally chemically roughened by pickling and by the subsequent, so-called electroless plating covered with a metallic layer and made electrically conductive.

The known drums differ according to their construction Characteristics or the type of their application, whether they are for the GaI- * vanizing of mass parts made of metals or plastics determined Bind. The different features or applications are also required for the different specific properties, which the bulk parts made of metals or plastics Identify. There are no known drums with, a single unchanged structural form and unchanged

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BATH ORIGINAL

permanent application optimal the functional conditions meet, which for daa either electroplating of bulk parts made of metals or plastics in one and the same drum both necessary than are also sufficient.

As a result - the lack of the technical standard and the solution according to the invention 3 and its advantages clearly to describe - defines the properties that are required for electroplating the electrolessly metallized plastic mass parts are specific. The same characteristics are for predominantly also for the electroplating of Ilass parts made of metals is vital.

The mass parts made of plastics, coated with an electrically conductive metal layer, float or float in the Electrolytes; but they can also sink to the bottom of the rotating container if the mean specific gravity of the individual plastic part is or has become larger than that of the bath solution.

The mean specific weight is the quotient of dividing the sum, formed by the weights of the Kimststoff part and its, continuously increasing metallic shell on the one hand and the entire body volume dea part on the other hand.

The specific weights of the plastics are usually lower than that of electrolysis (about 1.040 g / cm for ABS polymers or 1.120 g / cm 'for a cyanidic copper or 1.166 g / cm' for a nickel bath).

The mean specific weight of a, for example, disc-shaped part of the Maas (a button 22 mm in diameter and 4 mm thick) made of an ABS polymer with an electrolessly applied layer of 1 pm thick of copper (to make its surface electrically conductive) 'and another , electrolytically applied layer of 5 μm made of nickel (to achieve a mechanically abrasion-resistant and decoratively shiny coating) is 1.080 g / cm. The mean specific weight of the same part is, however, when applying a layer of 1 μm copper (to make its surface electrically conductive), a subsequent, electrolytically applied layer of 20 μm copper (for mechanical stiffening of the plastic part) and a layer of 5 μα nickel (to achieve a mechanically wear-resistant

209821 / 103Ö ~ ³ "*

as well as a decorative glossy cover) 1.213 g / cm. Of the specific (contact) pressure

for the electrical contact between two neighboring, plastic parts suspended in the treatment solution sonit - due to minimal differences between the mean specific weight of the parts by mass and the electrolytes - extremely small.

The specific contact pressure for electrolytic nickel plating is in the first example (1.080 g / cm - 1.166 g / cm =) - 0.086 g / cm and in the second example (1.213 g / cm ³ - 1.166 g / cm ³ ”) + 0.049 g / cm ³ . The negative sign indicates that the metallized plastic parts are floating in the nickel electrolyte and the positive sign that the parts in the nickel electrolyte sink to the bottom of the rotating drum.

Another necessary condition for galvanizing the uniform appearance of all batch parts. The parts must therefore always have both their mutual position as well as their position within the batch al Change the whole thing. The rotating container ensures a corresponding

Perfection j

the batch it contains and the plastic parts one

Relative movement

different speeds against each other. The metallic surfaces are generally not hydro « phob. The metal-like plastic part is therefore Electrolyte layer wetted, which as

liquid boundary layer

au solid body adheres and moves with desefi speed emotional.

The effectively effective electroplating of the rotating batch conglomerate, which consists of mass parts, takes place primarily on and in its peripheral zone Drum located) charge onf the field but breaks - according to the Faraday ¹ see cage effect - at the edge zone of the polarized charge and is capable

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only insignificant to penetrate into this. the

5. Breaking the electric field

limits the effect of the electrodeposition process a practically on the edge of the batch. It is known that a continuous exchange of the electrolyte on the cathodic surface especially the deposition of glossy layers is favorably influenced and by the Current air and oxygen or air bubbles that are formed on the surface of the mass parts are removed can set and prevent the metal reduction locally. The depletion of the electrolyte in reducible Metal ions and the formation of gas bubbles through hydrolysis mainly go in the area of the higher cathodic current densities, i.e. in the edge zone of the batch and thus at the Periphery of the rotating drum in front of you. It is accordingly

necessary the

6. Electrolyte (solution) exchange

mainly on the peripheral circumference of the rotating drum to intensify.

The phenomena described under points 1 to 4 have the consequence that a - conditionally avoidable - liquid film (an electrolyte layer) of different thickness is formed between the adjacent Masaenteile. The existence of the separating electrolyte layer leads to the formation
a. bipolar effects.

The electroplating current flows from the anodes located outside the drum (as the positive pole of the system) through the bath solution and the charge (more precisely through the metallic "skin" of the plastic parts) to the cathodic contact elements arranged in the rotating drum (all negative pole of the systems). If the individual mass parts are separated ("insulated") from one another by an electrolyte layer, the metallic shell on the individual plastic part retains the function of an electrical intermediate conductor; however, the mass part acts as a bipole within the batch. A region of its metallic surface has a cathodic potential and a — electrically diametrically opposed region — an anodic potential. Local galvanic cells are thus formed between the neighboring KunatstoiT parts that are in the flow direction of the galvanizing stream. Bipolar Effects

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but cause the - at least partial - Elektrolytiache Recirculation of the electroless and galvanically deposited Metal layers in those surface areas of the mass parts, which in the course of the. Rotational movement temporarily under anodic Stand potential. The bipolar effects consequently mean a reversal of the actual, desired galvanizing effect.

Bipolar effects also mean the electrolytic formation of metal oxides on the envelope layer (during their local anodic polarization); they therefore cause harsh as well matt surfaces unsuitable for decorative purposes.

The Ma3seriteile forming the Ohargen conglomerate prove points 1 to 4

inhomogeneous distribution of electrical potentials. The electroplating current is not distributed evenly; its course is confusing and uncontrollable. The consequences are an uneven appearance of the mass parts and - due to the decreasing potential differences of the individual parts of the Maas compared to the anode system - an essential one Decrease in the rate of electrolytic deposition (i.e. the electroplating performance).

Jkui innomogeneous electric potential field in the batch promotes the

chemical attack

of the electrolyte on the "Setallic coatings" of the plastic parts.

The chemically aggressive effect of the bath solution can result from the electrical refraction at the edge zone of the charge cannot be completely prevented and becomes considerable due to the possible formation of the separating electrolyte layers favored.

The attack means the chemical redissolution of the deposited metal and almost always the chemical oxidation of the Layer surface.

It is also the phenomenon of so-called burns

on the conductive layer or the electrodeposited metal envelope mentioned on the plastic parts.

The area of the fire is not punctiform, but flat and generally covers a considerable surface area.

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area of mass part.

The galvanic baths are much worse electrical conductors than the metals; the difference in their electrical conductivities corresponds to the order of magnitude of the ratio 1: 1O ⁵ .

It is - according to point a - with the emergence of local galvanic Cells to be counted between the neighboring mass parts. iJie power line is concentrated (in the area of the over going from one part to the other) initially to a spatial, almost punctiform interval, which: the electric oppositely polarized areas of two opposite mass parts (two adjacent metal shells} un: l encloses the intervening electrolyte film. It is known that Joule heat is the product of the electric Current I squared and the resistance R of the system is equivalent to. The resistance R is minimal when there are metallic bridges, i.e. when there are direct metallic contacts form part to part of the batch; but the resistance R jumps up suddenly when the current transfer 'over a poor electrical conductor, in this specific case must be done via the electrolyte film.

It must also be taken into account that on the anodic side of the (consist of two adjacent mass parts den) system a redissolution of the metallic layer and an oxidation of the surface takes place at the same time. the Metal oxides are known to be generally poor electrical conductors.

The effects described above are superimposed, causing a high total local resistance R and thus an excessive one local heat development; the poles are dark, purple-colored burn marks and circular gaps on the Surface of the mass parts that are partially or completely due to electrolytic and thermal effects - of their metallic covering layers can be covered »Dark Branci and de-metallized spots on the Mas a τι parts, which have lost their metallic coatings in some areas, occur in the case of the described and unfavorable radio, tion relationships according to points a to d are not singular. It is not all that uncommon for the industrial practitioner to have a completely unsuccessful batch in front of him and

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-it.-:

to have to watch out that mostly all mass parts - piece by piece Pieces - are unusable.

There are known drums of prismatic or cylindrical shape which rotate about their horizontal axis of symmetry, only to one Immerse a relatively small part of their volume in the electrolyte and use a centrally located opening (in one of the two end faces perpendicular to the axis of rotation), which are used for loading or unloading the batch of metallic mass parts serves. The opening basically remains during electroplating free; so it is not closed with a lid. Drums of the type described above are unsuitable for electroplating metallized plastic parts, because these float or float in the bath solution.

There are also drums of hexagonal, prismatic shape on Market have been introduced, which also rotate around their horizontal axis of symmetry and on their peripheral circumference (jacket) have an opening for loading or unloading the batch. The opening is closed with a cover during electroplating. The drums have a length of 550 mm and an average jacket diameter of 200 mm. The line of the electroplating current to the batch takes place via two insulated cables, which are individually fed through the two axial bearings (the end faces) are inserted into the drum interior and with bright metallic, cylindrical contact elements (200 mm long and 12 mm in diameter).

The drum described above can be structurally unchanged for electroplating mass-produced parts made of metal as well as under changed conditions of use - made of plastics will. If you galvanize metal parts by mass, you can completely or almost completely insert such drums into the Dip bath solution; However, dimensions are galvanized Plastics, so one has (according to Müller, G .: galvanizing ron Plastics, E.G. Leuze Verlag, Saulgau, 1966, pages 104 and 105 the same

^H ... only partially immersed in commercially available galvanizing drums, namely 1/3 to 50 $. This means that the goods are ^: forced to cluster on the bottom of the drum and constant contact is essential. However, only a very small volume of liquid is effective, the applicable current densities are very low, which means long exposure times

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results. Dar? permanent üufi auehen contacts au "liquid leads ^r: uv Vmr.-ivUirunn e J ta see ^one ri contact making""The gleinhi · Li 1 f rni IHFF ^<; 3] ο fi; j; i r1 · 'i .'- rrii ^ UMammonhang i'Aim Prob] em der GaJ vaiii'd ^ j uii / i from Κι; η? 5ΐ, / ίΐ f i'i ~ parts in the gnawed drums ausj

"The problem is to give the fabric a continuous, uninterrupted electrical contact, which for a einwandf rei e galvanizing require eh int. That's why sohwiei'ig because there ;? flume spesif i see weight of Kuußtötof I 'i ei If this leaves them wiinnior in relatively weak electrolytes, all mansen galvanizing devices located on the hardwood see in their construction that the (metallic) goods due to their own weight remain in permanent contact with the cathode contacts located on the bottom of the devices But this is not the case with plastic parts.

The obvious idea was to move the contacts up. Unfortunately, the buoyancy of the goods is not enough to ensure constant contact with the upward tax . Add to this that never goods heavier progresses metallization and begin to achweben in the liquid to eventually tax sinking ground. Since a 100 # filling of the drum volume is not possible, the goods move freely in the drum space and receive no or only partially electrical contact. This causes the formation of secondary propagation (note: of bipoles), which leads to the detachment of the chemical copper conductor layer. "

It corresponds to operational practice to fill the drums - regardless of whether they are mass parts made of metals or plastics - to one third to (maxima) half of their volume with the batch. Experience shows that larger amounts of powder - as a result of insufficient mixing of the batch - result in unevenly galvanized parts by mass and very long galvanizing times.

It should be added to the remarks in the literature on the disadvantages of the known drum that? the height of the electrolyte level "(of the liquid /; l: ei fsvoluniens in the tub aliso) or the · immersion depth of the drums (the height do.r mecliani solion structures on the Wannon rim 'Mir storage dnr ΤΐΊ-nimel) fitiuidi *: f, ehndt must ^be! r1, depending üachdoni, whether KaH ^ i 1.1 «i 1 e au :; plastics or

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BAD ORH31NAU

Galvanized metals, the low immersion depth of the Beschrtebeneri drum (from 33 to 50 % their »Voiumena) has only the consequence that during the rotational movement a considerable proportion - experience has shown about a fourth L - of the batch of plastic parts in the direction of rotation of the drum The bath solution is immersed in the bath and thus eludes the galvanizing process. The operating conditions described lead to inferior quality coating slips and thus often to rejects; the electroplating performance of the drum was low - due to small batch quantities and electroplating currents as well as long electroplating times. The previously cited parts of the literature assess (on page 107) the technical status of the galvanization of plastic parts in drums generally negative:

"It must be mentioned that in the case of bulk electroplating matt, but not high-gloss coatings can be achieved. "

A second type of drum (DBGM 1 997 988) has also become known on the market, with which one can choose from Electroplating both metal and plastic mass-produced parts in certain conditions, depending on the intended use can. The drum body has an octagonal, prismatic shape and also rotates around its horizontal axis of symmetry and has openings for loading on its peripheral circumference or unloading the batch. The opening is made during electroplating sierens closed with a lid. "The drum has one Length of 300 mm and a mean jacket diameter of 220 mm. The drum is built up according to the modular system; the device comes with a variety of accessories defined as Components delivered. For example, if the buyer intends to To galvanize plastic parts, he has to choose from the components forming the accessories Select the number and install them in the actual basic device. In the example of the electroplating of Plastic parts the installation of four so-called rod contacts (parallel to the axis of rotation), an inner cylinder, and an inner anode (both coaxial to the axis of rotation) and ' other components of secondary importance. If the next work step is the electroplating of metal parts, so are remove the aforementioned components from the drum and replace them with a set of other components that

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finally beabimmb for the galvanization of metallic mansion parts «Lnd, the complicated drum is extremely expensive, unhandy Lieh in use and - as operational practice shows - particularly vulnerable due to the large number of components For mechanical as well as electrical malfunctions, the success of electroplating depends on several, not or hardly controllable Puncture conditions (for example, on the presence eLnes constant electrical connection of the individual, chemically completely uninsulated contact rods) and the often insufficient ones Batch mixing from (due to the strong constriction of the interior of the drum by the, between the drum shell and inner cylinder and arranged parallel to these rod contacts). The drum is only for relative small, mainly spherical mass parts can be used; the geometric structure of the drum and its. Close dimensions

practically the electroplating of mass-produced parts, their dimensions Exceed 30 mm.

The drum according to the patent 3,330,753 of the Ver.St.vA »has the same basic construction as that according to DBGM 1 997 988 (consisting of the two end faces vertical to the axis of rotation, from which, between the said stern faces Shell, furthermore from an inner, concentrically arranged cylinder and several rod-shaped cathode contacts between the drum shell and the inner cylinder), with one essential exception, the inner anode. The American script suggests filling the interior of the drum with the batch to such an extent that the parts of the Maas can still move. The large amount of flush is intended to restrict the freedom of movement of the plastic parts as much as possible in order to force them to make electrical contact with one another. The electric field breaks (according to point 5) at the peripheral circumference of the large-volume charge; However, the majority of the mass parts are located within the conglomerate and are therefore effectively excluded from the galvanic heduction process and are increasingly exposed to the risk of bipolar effects, chemical attack by the electrolyte and the development of burns (according to points a, c and d). The inhomogeneous distribution of the electric potential field in the charge (according to point b) can be observed well in the practical application of the drum; and - for example - the parts by mass are relatively small, so can

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- «· - 1101332

you come home, open do 'drum ceiling] η and reaching into the change clearly see that the Hasaentei 3ο the peripheral extent ready "with r-lektrnlyti rope reduces em Hey tall covered and dit ^1', placed within dor batch parts little or not at all have been galvanized. The poles have exceptionally long electroplating times and unevenly appearing, matt to brightly shining electroplating coatings on the batch parts. As is well known, the electric field breaks at the peripheral periphery of the charge and the galvanic process takes place (according to point 5) practically in the hand zone of the conglomerate of parts by mass. The quantity P [dm J denotes the envelope _{surface ChO 1} (the surface area of the peripheral circumference) of the batch and Y [dm J ^inr volume, eo defines the quotient P / V [dm / dm J the mean value (i.e. the proportion ) of the electroplating current I, per unit of space of the batch volume a. If the value of the quotient is relatively high, the electroplating speed of the drum is also proportionally high.

The known drums discussed are with low mean values F / V of the electroplating current 1 marked. This common The disadvantage is - from a procedural point of view - of extraordinary importance; the consequences are very long electroplating times and therefore small electroplating of the drums, Another like amer and essentially procedural ethnic The disadvantage of the known drums consists in the low specific fish Contact pressure between the individual mass parts made of plastics as well as between these parts by mass and the cathodic contact elements. The frequently occurring poles are bipolar effects and an inhomogeneous electrical potential field in the Charge and thus burn points on the mass parts, chemical Redissolve the deposited metal and layers accordingly regular percentage rejects unusable galvanized Batch parts.

The considerable procedural disadvantages of the low mean values P / V of the electroplating current and the resulting therefrom Low electroplating performance also occurs when the batch consists of metallic parts by mass. The invention has the task of designing a drum ho that this with a single, unchanged constructive spatial form and unchanged application optimally fulfills the functional conditions, which

209831 / 103S " ^1? "

for the optional electroplating of mass-produced parts made of plastics or metals. The constructive solution should result in a simple, robust, high-performance drum with a clear structure and safe in its functional mode of action.
The object is achieved according to the invention in that

a. the length 1 of the drum measured parallel to the axis of rotation is smaller than that measured vertically to the axis of rotation Diameter D of the drum is

b. the end faces arranged vertically to the axis of rotation of the drum are provided with perforations.

In the case of drums with a polygonal shell cross-section, the diameter D represents an average value between the largest and smallest Distances of the polygonal sides from theirs. Center of symmetry represent.

The invention is characterized by the combination of two features; the first of these is the relation of the drum length 1 to the assigned diameter D.

The lengths and diameters of the known and previously mentioned drums behave as (550 mm: 200 mm =) 2.75: 1 or (300 mm: 220 mm =) 1.35 J 1, i.e. like fractions, their quotient is greater than 1. The quotient of the previously defined break is exceptionally greater than 1 for all known drums prismatic or cylindrical shape, which rotate around their horizontal axis of symmetry, for the most part in the bath solution immerse and have an opening for loading and unloading the charge on its peripheral circumference, which during the GaI-vanisierens is closed with a lid. The lengths of around 750 mm and diameters of around 325 mm such, all for The drums used for electroplating metal parts can be described as common; their relation is (750 mm: 325 mm =) 2.30: 1. It can thus be summarized be found that in the known drums, the length measured parallel to the axis of rotation is always greater than the assigned, is the diameter measured vertically to the axis of rotation. '

In contrast, the quotient of the breakage is always less than 1 in the case of the drums according to the invention.
The second, the drum according to the invention characterizing combination

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The national feature is the perforation of their front sides. All known and the drums described in the previous section have massive, imperforate end faces, which - if one is called Cable contacts for the transmission of the electroplating current used on the batch - have a central hole in the bearing.

It is particularly surprising that by reversing the generally applicable proportionality between length and diameter of the Drum on the one hand and through the perforation of the front sides on the other hand, especially the galvanization of the surface plastic parts made electrically conductive increases qualitatively and quantitatively by leaps and bounds compared to the known.

The surprising advantages of the drum according to the invention have been tested by comparative empirical tests. It was - as a comparable counterpart to the known drum according to DBGM 1 997 988 with a length of 300 mm and a diameter of 220 onwards - built a drum according to the invention, which has a length of 90 mm and a diameter of 400 mm. The volume of the two drums is the same (11.4 dm ') and they were filled with identical batches of identical hatch parts (buttons) made from an ABS polymer (2.8 kg batch weight, 5.8 de ⁵ batch volumes). The two batches were electroplated in a bright nickel bath, the electroplating currents and times as well as the speeds of the two test currents being the same. The nickel-plated mass parts from the drum according to the invention showed a high-gloss and flawlessly uniform appearance. The batch was free from rejects.

The mass parts from the well-known drum were predominant glossy, but showed more or less matt and matt-glossy tints in the central area of the disc-shaped buttons. The batch contained around 5 # scrap and uniformity the parts in appearance hardly lived up to a strict qualitative standard.

Samples of parts by mass that are periodically removed from the drum according to the invention during electroplating were taken, showed that their treatment was already after around 50 # of the otherwise required time (from 70 min in the known Comparison drum) was completed and that their coatings due to the continuation of the galvanizing process (up to

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209831/1039

to 70 min) could not be optimized in terms of quality. The special qualitative enhancement of galvanic coatings through the drum according to the invention was also confirmed by means of cuts through individual parts by mass. The cuts and carried out in such a way that the central holes of the buttons were divided lengthways. The wall (the small Holes 1.5 mm in diameter and 4 mm in length) were not found in the parts galvanized in the known drum or only covered with a matt nickel layer; the hole walls in contrast, the buttons from the drum according to the invention were coated with a layer of high-gloss nickel.

Another interesting observation related to the level of the electric DC voltage; it sank - at the same height as the galvanized steel röme - comparatively by a third in the case of the proposed drum. The following table gives an overview of the Electroplating times t, the electroplating currents I and the associated DC voltages U again; the tensions in the drum according to the invention are with the index e in the known Drum marked with b. The plating current I became periodically, proportional to the thickness of the metal Coating layers on the plastic parts increased.

t I Ue Ub

min A V V

20th 25th 2.0 3.5 10 45 2.5 4.5 10 - 70 3.5 5.5 30th 110 4.5 6.5

The above empirical perceptions allow the surprising conclusion that the three-dimensional shape of the drum according to the invention essential to improve the current transfer from the mass part to the mass part and from the mass part to the cathodic contact elements contributes. The proposed drum increases accordingly the specific contact pressure defined (under point 1), reduces or eliminates the electrolyte film between the individual parts by mass (according to point 4) and thus excludes the disadvantageous bipolar effects (according to point a), homogenized the electrical potential field in the batch (according to point "b b), throttles the chemical attack on the metallic coatings of the plastic parts (according to point c) and eliminates it

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the occurrence of burns (according to point d). The mass parts surrounded by the bath solution form the physical Pail of bodies immersed in a liquid; on the individual plastic parts, therefore, has a vertical effect Force directed upwards, which is called buoyancy and is equal to the weight of the volume of solution displaced by the mass part. The weight of the part and its buoyancy counteract each other.

The unusually large diameter of the drum according to the invention, which is around twice that of the known and comparable, this also results in the same proportionate filling quantities (for example one third of the drum volume) twice as high stacking (stacking) of mass parts One on top of the other, as in the well-known comparison drums. Appearance is shown in FIGS. 2 and 6. The lifting forces of those stacked on top of each other in the vertical Parts of the mass add up and the direction of their resultant points either to the level of the bath solution (as in Figure 2) or towards the bottom of the drum (according to Figure 6), depending on whether the parts float or sink in the electrolyte. If the "column" of the mass parts stacked on top of one another is higher (longer), the resulting mean contact pressure is also higher larger within the batch. Thus, in the specific case, the diameter of the drum according to the invention is twice as large as that of the known ones, and the two comparable drums are, for example, one third of their volume with parts by mass filled, this is the average batch height - and thus the average, specific contact pressure between the plastic parts - in the drum according to the invention approximately twice as large as in the known (regardless of whether the mass parts float or sink to the bottom of the drum).

The above statement shows - in connection with the surprising procedural advantages of the invention Drum - the extraordinary importance of the contact pressure between the individual batch parts in galvanizing of plastic parts. The perforation of the front sides (as a second, essential feature of the invention) opens the way for the electroplating current in one. Area that is blocked (blocked) in the case of the known drums is. The edge zones of the charge, which ran against the end walls of the drum, thus become electrolytic according to the invention

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activated and thus effectively integrated into the electrodeposition process. If the dimensions of the test drum according to the invention (with a length of 90 mm and a diameter of 400 mm) are taken into account as an example, the activation of the edge zones of the charge adjacent to the two end faces means an effective increase in the electroplating performance . approximately three times as much (surface of the drum shell: H400 mm.90 mm = 11.3 dm, surface of one end face: ¥ (400 mm) ^2/4 = 12.8 dm ² , drum volume: 12.8 dm ² .90 mm «■ 11.5 dm ^). The mean value P / V Jdm / dm ^ j of the electroplating current is - if the front sides were not perforated - equal to (11.3 dm ² : 11.5 dm ⁵ =) 0.98 dm ² / dm ⁵ and reaches - with perfo-

P " ¹ I

faved end faces - the value (36.9 dm: 11.5 dnr =) 3.21 dm / dm; the specific amount of the electroplating current each Unit of space of the batch volume (the deposition rate so) surprisingly increases as a result of the measure according to the invention around three times.

The upper plague position shows - again in connection with the advantages the drum according to the invention - the, likewise extraordinary. Meaning which also the perforation of both Front sides for intensifying the galvanization of ground parts made of plastics (or metals).

An advantageous embodiment of the invention provides that Arrange anodes parallel to the perforated end faces. It has been found that the arrangement results in a homogeneous distribution of the electric field in the electrolyte between the rows of anodes and those adjacent to the perforated end faces of the drum Edge zones of the batch leads. The large anode surfaces, which result from the fanning of the anodes along of the two end faces contribute to the fact that the anodic current densities are distributed relatively constant - despite the very large electroplating currents - do not exceed their upper permissible limit and thus do not cause any passivation phenomena. The parallelism of anodes and cathodes represents the ideal borderline case to be striven for when setting up galvanic Systems (cells) represent; the idea of the invention forms a practical step in this direction. Great active Anode surfaces, area-related constancy and the mean increase in anodic currents mean high electroplating currents and small tensions; they are the prerequisite for

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the considerable increase in the speed of galvanic separation and uniformity of the metal layers on the mass parts.

The inventive arrangement of further anodes along the perforated Mantle (parallel to the rotation aachae) of the drum a completing purpose; They contribute to the increase dee Galvaniaieratromea and for homogenization dee elektriachen Field in the peripheral area of the drum. According to the rotation movement (in the specific Beiapiela cases of Figures 2 and 6 from left to right) in the drum; it is thus removed from the one row of anodes, arranged along the jacket, approaches the diametrically opposite one and remains in the eccentric one Company call during the entire duration of the treatment. The local cathodic current densities on the perforated drum shell (and along the pallines m-n in Figures 2 and 6) and the local anodic. Current densities at those associated with the jacket Anodes vary considerably in their values; they depend functionally on the assigned distances (in the electrolyte) between the polygonal jacket and the vertically hanging anodes. The inequality of the anodic and cathodic Current density is characteristic of electroplating in the well-known drums; Measurements have shown that (in the ,, Examples of FIGS. 2 and 6 representative of operational practice) the galvanizing current between the two of the left and right - anode row distributed as 1: 2. The inventive arrangement of anode rows along the Front sides and thus the relocation of the electroplating focus of vision in those areas of the drum system, their spatial parallelism Granting a homogeneous electric field leads - including the supplementary Galvaniervorganga in the cladding area - to one characterized by extensive uniformity electric field on the entire periphery of the drum body. That, preferably completely in the bath solution Submersible drum is on all sides (both in the area of the perforated end faces and the perforated jacket) of anodes surrounded by an electrical field of high homogeneity envelops the charge on its entire surface to an intensive and even electroplating process result in favorable functional conditions - even with batches

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from metallic mass parts - to very high electroplating currents at technically permissible cathodic and anodic current densities and continue to reproduce in extraordinary high electroplating speeds with excellent quality Coating layers.

The electrical PeId breaks (according to point 5) at the edge zones of the batch and is only able to penetrate it insignificantly. Pie perforated end faces offer the advantage that the field from two diametrically opposite sides (from the two end faces) into the conglomerate of mass parts sprinkle into it and - due to the short length of the drum - the scattering force acts deep enough into the interior of the batch may to be of technical importance. The small distance between the two edge zones, which are parallel to one another, is also a factor to superimpose and reinforce the field penetrating from two opposite directions within the narrow Charge, and thus to even galvanic deposits on the mass parts (regardless of whether they are made of plastics or metals). An analogous statement applies to the electrical Peak dispersion of those assigned to the end faces and not anode rows far from each other on the edge zone of the charge adjacent to the drum shell.

Another advantage that characterizes the drum according to the invention is the effective mixing of the metal parts by mass or plastics. The surface of the charge that is not in contact with the drum shell inclines in the direction of rotation (according to the straight line m-n drawn in Figures 2 and 6). The mass parts roll loosely along the fall line m-n. The unusual large diameter results in a long fall distance and thus forces intensive mixing of the parts that make up the Must go through the way from the place m to the place η. The very short length of the drum, on the other hand, forms a narrow path between the two end faces; those, during the rumble on the end walls rubbing mass parts are hindered in their movement compared to the freely falling parts and the mixing effect of the batch further increased.

The small length of the drum offers - especially for mass-produced parts made of metals that form batches of large weights - significant structural and price advantages. The mechanical structure simplifies; the elaborate corner stiffeners on the drum shell (parallel to the axis of rotation) and the carrying and supporting

209831/1039 - 19 -

1101332

at the openings for loading and unloading the batch be dimensioned weakly (or omitted). The lid is short, rigid and easy to attach to the openings. The wall of the drum shell can be thinner and with a larger open passage area (with a denser perforation) for higher electroplating currents and efficient fluid exchange can be built.

The front sides are large and - for reasons of mechanical Strength - significantly thicker (generally five to six times stronger) than the drum shell. The perforations in the end faces are generally aligned horizontally and fill with electrolyte in the bath solution. It it was found that when the drum is lifted out of the liquid, the perforations - due to capillarity - with electrolyte stay filled. The invention suggests the length of the perforation holes to be considerably shorter than the thickness of the end faces in which they are located. The measure according to the invention prevents significant amounts of liquid from being discharged when the drum is changed from one bath solution to the next and thus limits the loss of bath chemicals and contamination the electrolyte significantly. It has also all been found advantageous, disc-shaped, perforated Manufacture inserts from an electrically non-conductive material by injection molding and in large, cylindrical Fixing holes in the end faces interchangeably. A preferred embodiment of the invention provides that Length 1 of the drum, measured parallel to the axis of rotation, preferably less than half of, vertical to the axis of rotation measured diameter D of the drum. The further shortening of the length 1 intensifies the penetration of the charge with the electric field scattering in from both perforated end faces and promotes the effective Mixing of the parts by mass during the rotational movement.

The unusually large diameter of the troinmel-coats (from 400 mm in the representations of Figures 1, 2 and 3 or 600 mm in Figures 5, 6 and 7) result in large, disc-shaped end faces. It was made - primarily - for functional reasons Application in the electroplating process as well as - secondary - from constructive Reasons found to be advantageous, the two front sides

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209831/1039

geometrically flat and with no opening »in order to or unloading of the charge in the central, (rotational) axial area of the drum body. Rather, it turned out to be proved advantageous to arrange the opening on the peripheral circumference (ie on the jacket) of the drum. The opening of the invention The drum is therefore not in the central area (not in the middle) of the drum housing, which consists of the end faces and the jacket but provided on its peripheral circumference (i.e. on the jacket); their location enables uncomplicated loading and unloading of the batch. The opening is always blocked with a (removable) disgust during electroplating; the Tronmel interior is consequently during the entire treatment time completely closed.

Are the drums according to the invention for electroplating Used by plastic parts, they are generally two, diametrically opposed and on the peripheral jacket the drum located openings provided. Practical experience has shown that when the known drum! from the bath solution individual parts wetted with liquid (due to their low weight) in loose form on the wall stick and delay a quick, complete discharge of the batch. It is against this in the case of the drum according to the invention possible to turn one of the two openings to its lowest position and to pass the mass parts through this, by means of a (through the upper second opening introduced) to evacuate the water jet quickly.

It has also been found that the best procedural Effects can be achieved when the drum - regardless of whether the batch consists of metal or plastic parts - is completely or almost completely immersed in the electrolyte. Are the parts made of metal (or are the plastic parts sinking to the drum base), their location below the solution level - together with the assigned anode system - enables the formation of a batch periphery from all sides enveloping electrical field of high homogeneity.

It is also mentioned in the literature cited at the beginning (on pages 105 and 106) describes an apparatus for electroplating plastic parts, the perforated container for the Chargenaui'nahme has a bell shape and around its, to the horizontal

moderate symmetry 209831/1039

len rotates by about 45 ° inclined symmetry axis. The floating ones

(or plastic parts that sink to the bottom of said bells) remain as stationary, immovable and compact mass always in the top (or bottom) zone of the rotating bell. Rotations around axes whose position is significantly different from the horizontal deviates are unsuitable for achieving an intensive mixing effect. In contrast, the invention is characterized in that that the axis of rotation of the drum is arranged horizontally or almost horizontally. The overturning of the horizontal rotating drum forces effective mixing movements within the batch and thus permanent changes in the location of everyone Share with each other.

Another particularly advantageous embodiment of the invention provides for the arrangement of a cylinder within the drum housing before. The preferably hollow inner cylinder has a circular one or polygonal cross-section, extends from one end of the drum to the other and rotates in synchronism with the drum body around the common axis of symmetry.

The batch of plastics or metals floats or sinks in the bath solution and pushes either the top or the room the lowest zone of the drum, which is usually completely submerged. If the drum has an inner cylinder, see this it comes to one

A. Doubling the batch size.

According to the invention, approximately two thirds of the annular interior of the drum is filled with the maize parts. The inner cylinder is completely surrounded by the charge floating in the bath solution (see FIG. 2) or sinking to the bottom of the drum (see FIG. 6) and on its lower side (along the line mn in FIG. 2) or on its upper side Side (along the line mn in Figure 6) only . covered by a thin layer of parts by mass.

The double batch quantities mean a quantitative doubling the drum performance ..

The interior that remains free (not filled with mass-produced parts) the drum secures an extremely

B. intensive mixing

of the batch. The parts slide over the inner tube (along the lines mn in FIGS. 2 and 6) and change their position both mutually and within the batch as aisle. Improved mixing means improved

209831/1039 " ²² "

The uniformity and quality of the metallic coatings the mass parts.

The batch parts are received temporarily and periodically

C. fixed positions ^v

within the conglomerate formed from parts by mass. Each part retains its position both in relation to the neighboring ones Mass parts as well as with respect to the drum housing and the cathodic contact elements during the period of rotation Except for the time when he is tumbling down the mixing interval (along lines m-n in Figures 2 and 6) Mixing with the other mass parts happens. The batch as a whole does not move relative to the Drum housing off.

The fixed position prevents (for around two thirds of the treatment time) all shifts between the individual parts that are in contact with one another; the thickness of the disadvantageous electrolyte film - according to point 4 - between neighboring mass parts (as well as between the parts and cathodic contact elements) is considerably reduced or the film is pierced by direct physical contact between the neighboring parts (production of direct electrical contacts between the ground parts via metallic bridges). Abrasive removal of the extremely thin, electrolessly reduced metal layer (generally 0.8 μm thick in order to make the surface of the plastic parts electrically conductive) and its partial (re) dissolution due to chemical and electrolytic effects are particularly important in the The first, critical phase of the electroplating process is reduced to a minimum. Furthermore, the causes and the emergence of the bipole effects characterizing the bulk electroplating of plastic parts (according to point a) and pairing of the cathodic contact elements (due to excessive current densities on these) are largely reduced locked out.
Of the

D. specific electrical contact pressure

between the floating or sinking parts of the mass is as stated under point 1 - extremely small, but of primary importance for the transmission of the relatively high electroplating currents (generally over 100 A). The doubling of the batch quantity increases the mean specific contact

209831/1039 - 23 -

β «101332

pressure almost directly proportional; the doubled buoyancy (for floating parts) or "downforce" force . (with decreasing parts by mass) contributes significantly to the accelerated as well as safe execution of the electroplating process.

The spatial, ring-shaped distribution of the charge in the drum and the comparatively large diameter of the drum shell result in approximately twice the size of the batch envelope; the double batch enveloping surfaces thus make it possible one

E. Doubling the electroplating current a
and therefore

a doubling of the electroplating output per drum. The explanations under points A to E place the extraordinary important advantages for the electroplating of mass parts made of plastics or metals, which result from the inventive Arrangement of an inner cylinder in the proposed drums result.

The procedural requirements for achieving the advantages described under points A to E can best be achieved when the drum is completely immersed in the bath solution and the batch of parts by mass at least partially covers the surface of the inner cylinder. The statement applies particularly to floating plastic parts; the completely immersed drum prevents the parts of the mass, which are striving upwards due to buoyancy, from emerging from the electrolyte and thereby evading the electroplating process. The favorable poles are uniformity in the appearance of the batch parts and quantitative and qualitative increases in the electrolytic metal deposition.

The inner cylinder usually consists of an »electrically non-conductive material and is preferably provided with perforations. The electric field between the perforated end faces and the associated rows of anodes scatters through the perforated inner cylinder and penetrates the hand zone of the batch that is in contact with it. The perforation of the inner cylinder thus increases the sum of the active peripheral charge areas and increases the

Electroplating performance of the drum.

Are mass parts made of metals or plastics (which, due to their specific weight, have particularly strong buoyancy or

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" ^{Output M} -forces) galvanized, it was found to be beneficial to design the inner cylinder as a cathodic contact element. The same contact shape also proves to be beneficial when the individual mass parts have relatively large dimensions and it is advantageous for the mixing process, the ring-shaped To keep the space between the drum shell and the inner cylinder free of components (i.e. also free of cathodic contact elements).

Are mass parts from plastics galvanized, according to the their * specific weight weak buoyancy or "downforce" forces have or tend to float in the bath solution, see above is the arrangement of a ring-shaped cathodic contact element in the middle of the annular, between the peripheral drum shell and the inner cylinder, which is also made of an electrically non-conductive material, has been found to be favorable. FIG. 2 shows that in every longitudinal section of the drum and in every phase of movement of the batch in the middle of the parts located contact ring.

The arrangement of an annular contact ring realized together With the described features according to the invention practically the Yo out set exercises that address the problem for electroplating of bulk plastic parts are based on:

Largest possible active enveloping surface of the batch, even distribution of the maximum permissible cathodic current densities over the entire enveloping surface, cathodic contact elements that are as large as possible, spatially distributed and located within the batch, the shortest possible paths for the electroplating drum through the batch from its active hand zones to the cathodic contact elements ,

»As far as possible high contact pressure between the parts and against each other the cathodic contact elements.

The small length and the large diameter result in a disc-shaped one Three-dimensional shape of the drum according to the invention. The shape enables - as a further advantageous and important embodiment of the invention - the mutually parallel, coaxial arrangement of two, three or more of said drums, all on a common axis or on separate axes can be stored in the same alignment and preferably rotate synchronously. The drums form constructive units, which the

209831/1039 - 25 -

Names "Gemini ¹¹ - or ^H Triplets" received Iroi? Jinel. The inventive combination of said drums to form such units represents a significant advance over the known. Patent 3,038,851 of Ver.St.vA shows - for example - the complicated, expensive and electrolytically ineffective structural design of a known ^M quadruple "drum The individual drums belonging to the unit according to the invention can be filled at the same time with batches of different types and sizes; one can thus - for example in a twin drum - galvanize batches of mass parts made of metal and plastics at the same time forming drums - in the sense of the invention - arranged rows of anodes which are attached parallel to the end faces. The distance between the rows of anodes and the perforated end faces is always less than twice the drum length 1. The usual speed of the known drums t'ends to 8 revolutions per minute. High speeds cause high relative speeds between the neighboring mass parts. If the parts are made of plastics, the poles can be bipolar effects and thus - due to partial anodic polarization - rough and matt surfaces of the galvanic coating layers in some areas. If the batch consists of metallic screws, electronic components or other relatively sensitive mass parts, the relatively high speed can lead to mechanical damage due to impact. The large diameters of the drums according to the invention permit low speeds without impairing the intensity of the batch mixing. It is therefore proposed that the speed of the drums according to the invention is less than 8 revolutions per minute.

The invention is explained with reference to drawings. Show it as examples the

Figure 1 shows the longitudinal section of an embodiment of the erfindungegemäSen Drum, which is particularly suitable for electroplating mass-produced plastic parts, Figure 2 shows the associated cross-section and

Figure 3 shows the associated plan of the drum according to the Pigur 1,. FIG. 4 shows two views of a perforated, disk-shaped insert (which is fastened in the end faces of the drum),

- 26 -

209831/1039

Figure 5 shows the (partial) longitudinal section of a so-called twin

lings drum according to the invention, Pigur 6 the assigned cross-section and Pigur 7 the assigned floor plan according to Pigur 5. The drums shown rotate counterclockwise around their axis of symmetry (in the direction of the arrows in the Figures 2 and 6).

The drum of the Pigur 2 contains a batch 1, the parts of which are made of plastics and float in the electrolyte; the drum der-Figure 6 contains a batch 1 made of plastics or me- · metallic materials which have a higher (average) specific weight than the bath solution and to the bottom of the drum sink. The mass parts 1 tumble during the rotational movement along the fall sections m-n and mix. All of the exemplary embodiments shown in FIGS. 1, 2, 3, 5, 6 and 7 concern drums that are in unchanged constructive Raumfora and unchanged application both for electroplating can be used by mass parts made of plastics as well as metals.

The drum unit is generally designated by the ordinal number 10. It preferably consists of a prismatic housing with a polygonal or circular cross-section and has a pair of parallel end faces 11 arranged at a distance from one another. The end faces 11 are perforated; the length of, horizontally aligned perforations must be smaller than the thickness of the end faces 11. The end faces 11 of the exemplary embodiments in FIGS. 1, 2, 5 and 6 have honeycomb-like distribution, large cylindrical holes in which disc-shaped and perforated inserts 12 are attached.

FIG. 4 shows an insert 12 with its most important details again. The disc 12 has a reinforced, circular edge and is - to the Innenrauxa of the drum 10 hj.n - concave arched, in order to absorb the mechanical pressure of the (metallic) charge directed perpendicular to its plane and to pass it on to the end face 11 by elastic deformation. The stakes 12 are generally manufactured in the injection molding process from an electrically non-conductive material and in the bore of the Front face 11 preferably exchangeably fastened by mechanical pressing, by welding or gluing. The drum shell 13, which is usually provided with perforations,

- 27 -

209831/1039

stretches between the front sides and it is rigid tied together.

The letter 1 shows that, parallel to the axis of symmetry and rotation measured length, while the letter D is the diameter of the drum according to the invention, measured vertically to the axis. It always applies that the length 1 is smaller than the diameter D; a particularly advantageous (can be seen in Figures 1, 3, 5 and 7) Embodiment of the invention dimensioned the drum length 1 less than half of the diameter D. Circular perforations are indicated with groupings of small circles in FIGS. 1 and 3 and with the ordinal number 2, whereas the perforations of square cross-section in FIGS. 2, 4, 5, 6 and 7 are marked with the number 3.

The jacket 13 has the openings 14 for loading or unloading the drum 10 with the batch 1 to enable. The openings 14 are closed with the removable lids 15. Die Lids 15 are perforated and are often fastened to the drum shell 13 with elastically resilient tabs 16 made of titanium. The drum 10 has in the embodiments of Figures 1 and 2 two, diametrically opposed openings -14 to allow the emptying of the Charge 1 to make it easier and faster.

The peripheral circumference of one of the two end faces 11 is provided with the ring gear 17, which the torque of the motor drive (from a motor source not shown) takes over by the pinion 4 and sets the drum body in the rotating motion.

The end faces 11, the drum shell 13 and the cover 15 are Made of electrically non-conductive materials that are chemically resistant in the various treatment solutions (electrolytes) manufactured.

Figures 1, 2, 3 as well as 5t6 and 7 show two different rows of anodes, a row 5 parallel to the end faces 11 and an anode row 6 parallel to the axis of rotation of the drum 10. The Rows of anodes 5 and 6 surround the drum body 10 from all sides, like an envelope surface.

The perforated inner cylinder shown in FIGS. 1 and 2 18 preferably consists of an electrically non-conductive one. Material is preferably coaxial within the drum shell 13 arranged and extends from one end wall 11 to the opposite one. The diameter of the cylinder 18 is with the

209831/1039

Marked with letter d.
The ring-shaped cathode contact 19 located inside the drum housing transmits the electroplating current to the batch 1. The (actually sickle-shaped double) ring contact 19 offers a large contact area and is located in every longitudinal section of the drum 10 and in every phase of movement of the batch 1 within the hatch parts . The support legs 20 of the cathode element are insulated from the bath solution and the electrical field with a chemically resistant, electrically non-conductive sheath 21.

The drum 10 in Figures 1, 2 and 3 is at right angles curved support arm 22 carried, which terminates in a horizontal stub. The, with the screw connections 23 to the Both support legs 20 attached disk-shaped and tubular components (made of a suitable plastic) 24 and 25 form

"the bearing axis on which the drum 10 (consisting of the both end faces 11, the jacket 13, the two covers 15 and the inner cylinder 18) rotates. The contact ring 19 »the support legs 20 and the curved support arm 22 form a seamlessly connected, rigid metallic body, which the function the mechanical drum bearing and power supply and transmission to batch 1 (and - together with components 24 and 25 of the bearing axis - the non-rotating, i.e. stationary part of the drum system). The support arm 22 is likewise protected with the insulation 21 and provides the connection to the negative pole of the direct current source. It is possible within the meaning of the invention, the inner cylinder 18 as

) to use cathodic contact element. The cylinder 18 is made of a conductive material and thus forms a so-called cylinder contact, which the electroplating current to the Charge 1 transfers. The metallic cylinder 18 is supported, for example, on the two support legs 20 and on its inside with the jacket 21 chemically and electrically isolated from the bath solution.

Figure 2 shows a floating charge 1, which the interior the drum fills around two thirds and completely covers the inner cylinder 18. Charge 1 is then the cheapest dimensioned when the cylinder 18 is barely covered by the mass parts 1 and hardly enough for the mixing process the part 1 remains free. The mass parts 1 rumble during the

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209831/1039

"ST · ·· -: i 1101332

Troinme oil rotation over the cylinder 18 (along the drop line m-n) and have an excellent mixing effect. FIGS. 5, 6 and 7 show the drums 10 according to the invention, which are arranged in parallel and which are rotated around a common hollow axis 26 rotate. The individual drum shells 13 (and lieckel 15) exist made of plastic plates 27, which have staggered, interlocking eyelets at their ends and are joined together with the bolts 28 as well as being held. The two ends of the bolts 28 are in turn anchored in the end faces 11. The plates 27 have square perforations 3t they are injection molded (made of polypropylene, for example) and are therefore cheap and modularly interchangeable.

The cover 15 is likewise formed from two such plates 27 and detachably attached to the drum shell 13 with the flexible closure 16 (made of spring-hard titanium sheet metal). The batch 1 in the drums 10 of Figures 5 »6 and 7 can both consist of plastic parts with a higher average specific weight (sinking towards the bottom of the drum) as well as of metals. If the drum is used for larger metal parts and heavy batches, so their diameter can advantageously be 3 very large, for example D = 600 mm and the associated length 1 = = 150 mm.

The electroplating current flows through the insulated cables 29 from the DC power source to batch 1; the two bare metal contact bulbs 30 put the mass parts 1 under cathodic polarity .

The end faces 11 have the bearing bushes 31, which on the hollow axle 26 (made of a titanium tube) rotate. The axis 26 is at its ends by the two vertically arranged support arms 32 (made of titanium tubes with a square or right-angled cross-section). The cables 29 are within the pipe system (from the components 26 and 32) laid and protected against mechanical damage. The ring gear 17 is only on the mounted below the pinion 4- arranged drum 10. The rotary movement is driven by the first by means of the ring gear 17 Transfer drum 10 through the couplings 34 to the other two drums 10 of the drilling system. The support arms 32 (or the drum support arm 22 of FIG. 1) are rigidly fixed to a support frame 33 which, together with the drum (s) 10, is a transport unit (examples)

- 30 209831/1039

"j ■.: ··: 2: 1O1332

wise a triplet tromael) oiHden. Dae Geetel] 33 has Corresponding mechanical and electrical systems 35 »to be placed on the stiffening edges of the tubs 7 and the rotating To be able to connect drum 10 (in the submerged operating state) to the direct current source.

The drum according to the invention is also particularly advantageously suitable for pickling, for electroless plating as well electrolytic metallization of batch 1 from plastics as well as for the so-called anodic polishing of metallic mass parts. ·

The structural design of the drum 10 according to the invention does not preclude the possibility of being inside the inner cylinder to arrange a soluble or insoluble inner anode. When the drum 10 is used for anodic polishing, it occurs an electrical polarity reversal of the charge 1, the contact elements 19 or 30 and the anodes 5 and 6. That means in concrete terms Case that the batch 1 together with the, now anodic contact elements 19 or 30 the positive pole and electrodes 5 and 6 in the tub 7, the cathodes, so form the negative pole of the system. The inner anode, if present, is transformed into a Inner cathode around. *

The drum 10 is immersed in a bath solution which is contained in the tub 7. Is electroplated in tub 7 (or anodic polished), the anodes (or cathodes) 5 and 6 hang from the rods 8 in the electrolyte.

The circular and square perforations 2 and 3 are supposed to be made as close as possible to a large open passage area in the end faces 11, the jacket 13 and the

.0 "

Form cover 15. Large passage areas (greater than 15 · i proportion of the total drum surface) allow high Galvaniaierströme and - in the area of the individual perforation holes - locally uniform and disperse, and thus favorable current distributions at the electrolytically active Randzoneη the batch. 1

The horizontal line in the upper area of all representations of the tubs 7 symbolizes the height of the liquid level.

209831/1039

Claims (1)

Claims; Drum for electroplating loose bulk parts made of plastics or metals, possibly also for pickling and electroless metallization of bulk parts made of plastics or for anodic polishing of bulk parts Parts by mass of metals, completely or almost completely immersed in the electrolyte, mainly of a pair end faces more distant from one another, preferably vertical to the axis of rotation of said drum, and off consisting of a peripheral, prismatic or cylindrical jacket fixed between said end faces, wherein the housing of the drum consisting of said end faces and said casing on its peripheral circumference at least one serving for loading or unloading the mass parts to be electroplated and during electroplating is provided with an opening to be closed, characterized in that a. the length 1 of the drum (10) measured parallel to the axis of rotation is smaller than the associated length 1, vertical to the axis of rotation measured diameter D of the drum (10), b. the end faces (11) arranged vertically to the axis of rotation of the drum (10) are provided with perforations. Drum according to Claim 1, characterized in that the anodes (5 ) located outside the drum (10) are assigned to the end faces (11), preferably vertical to the axis of rotation of the drum (10) and thus parallel to the perforated end faces (11) . Drum according to Claims 1 to 2, characterized in that the peripheral casing (13) of the drum (10) and optionally the lid (15) are perforated. Drum according to Claims 1 to 3, characterized in that that the additional anodes (6) are assigned to the drum shell (13), preferably parallel to the axis of rotation of the drum (10) and thus arranged parallel to the perforated jacket (13) Bind. - 2 209831/1039 5. Drum according to claims 1 to 4, characterized in that that the lengths of the perforation holes in the walls of the end faces (11) are equal to or less than threefold that Wall thickness of the jacket (13) and / or of the cover (15) are dimensioned. 6. Drum according to claims 1 to 5, characterized in that that the length 1 of the troamel (10) measured parallel to the axis of rotation is preferably equal to or less than half half of the assigned, measured vertically on the axis of rotation Diameter D of the drum (10) is. 7. Drum according to claims 1 to 6, characterized in that the opening (H) for loading or unloading the drum (10) with the charge (1) arranged on the jacket (13) and during the Electroplating time is closed with the associated, removable cover (15). 8. Drum according to claims 1 to 7, characterized in that the angle between the axis of rotation of the drum (10) and the horizontal is less than 30 °. 9. Drum according to claims 1 to 8, characterized in that the drum (10) has a, within the peripheral shell (13) located, preferably coaxially to the axis of rotation arranged inner cylinder (18) polygonal or circular Contains cross-section. 10. The method according to claims 1 to 9 »characterized in that that the charge (1) of parts by mass at least partially covers the surface of the inner cylinder (18). 11. The method according to claims 1 to 10, characterized in that that the drum (10) is completely immersed in the electrolyte. 12. Drum according to claims 1 to 11, characterized in that two, preferably diametrically opposed openings (H) for loading and unloading the drum (10) bit of the Charge (1) are arranged on the jacket (13) and during the electroplating period with the associated, removable covers (15) be locked. 13 · Drum according to claims 1 to 12, characterized in that the inner cylinder (18) consists of an electrically non-conductive. consists of the material and is preferably provided with perforations. 209831/1039 14 ·. Drum according to Claims 1 to 12, characterized in that that the inner cylinder (18) as cathodic contact el an nt is trained. 15. Drum according to claims 1 to 13, characterized in that the, within the annular space between the peripheral Jacket (13) and the cylinder (18) made of an electrically non-conductive material and located cathodic Contact element is designed as a King (19). 16. Drum according to claim 1 and one or more of the claims 2 "to 15, characterized in that two or more, parallel to each other and coaxially arranged drums (10), which preferably rotate synchronously, for example as a double or triple drum, forming a unit. 17. Drum according to claim 1 and one or more of claims 2 to 16, characterized in that the distance from the The anode row (5) to the associated end face (11) is less than twice the length 1 of the drum (10). 18. Drum according to claims 1 to 17, characterized in that the disc-shaped perforated inserts (12) from one electrically non-conductive material, preferably by injection molding are produced and fastened in the end faces (11), if necessary, interchangeably. 19 · Drum according to claim 1 and according to one or more of the claims 2 to 18 ', characterized in that a preferably concentrically arranged, soluble or insoluble inner anode is located. 20. Drum and method according to claim 1 and according to one or more of claims 2 to 19, characterized in that the one and the same drum (10) for pickling, electroless plating and electrolytic plating of the Batch (1) made of plastics is used. 21. Drum and method according to claim 1 and according to one or several of claims 2 to 19, characterized in that the contact elements (19, 30) the anodic pole and the electrodes - (5, 6) outside the drum (10) the cathodic pole form, and the drum (10) is used for the so-called anodic polishing of the metallic mass parts (1). 209831/1039 3H. Blank page