IL26350A - Method of surface treatment and device for the practical application of said method - Google Patents

Description

'mini inn TJinj"! m PATENT ATTORNEYS · D'QIDS 'DUD DR. REINHOLD COHN ¾f) /*->%« ΜΊΜΠ f*^!H |Π 3 11ΙΠΙ» T ■ Π DR. MICHAEL COHN ggV, Ό¾ ULJ [ } ^fl 1Π3 *) N 31 D It ISRAEL SHACHTER B.Sc. ■ D 3 Ί B 3 Ul -J N Ί HI · File C/ 25091 PATENTS AND DESIGNS ORDINANCE SPECIFICATION Method of surface treataent and device for t!i© practical application of said $s%ftitiU>m 1 (we> COMMISSARIAT A 'L*IS5K9IS ATOMIQTJS* a French company of 29 rme de la Fed©ratioa, faris 15 » France do hereby declare the nature of this invention and in what manner the same is to be performed, to be particularly described and ascertained in and by the following statement :- The present invention is directed to a method whereby electrically conductive parts are subjected to an electrolytic or chemical surface treatment whioh io at least superficial and is further concerned with a device for the practical application of said method ; both said method and said device are of interest for the complete treatment (degreasing, pickling, washing and metal coating) of uranium parts or parts formed of a uranium base alloy „ The principle of electrolytic surface treatment of electrically conductive parts is well known ; the parts to be treated are immersed in a bath of suitable composition and constitute one of the electrodes of an electric circuit which is closed by electrodes placed in the batho By sending an electric current through the bath, a number of different treatments can be carried out such as pickling, coating with metal and so forth . 15083 ffremah Patent N" -1 260 086 ao grantod to OOMMISDAniAT A L'ENERGIE ATOMIQUE describes a method for the electrolytic surface treatment of parts of revolutio . This method consists in supporting the parts to be treated within a helical spring which is disposed horizontally in the bath and through which electric current is supplied to the part, and in causing said spring to rotate during the operation so as to modify the zones of contact between the spring and the part to be treated while ensuring uniformity of treatment over the entire surface of the part.

Unfortunately, this solution is not always applicable to the treatment of parts which are not of revolutio . In particular, in the case of parts having a cress-section of polygonal configuration, the part which is placed inside the helical spring slides along the coils of the spring instead of rotating, which consequently destroys the advantage of the solution proposed by the French patent.

The present invention is directed to the basic concept of a method which can be applied to parts having a cross-sectional configuration which is not circular and especially to parts of polygonal cross-section » With this object in mind, the invention proposes a method of chemical and/or electrolytic surface treatment of prismatic parts each having in cross-section n long sides of substantially equal length, said method consisting in supporting the part to be treated on the lower portion of a coiled spring having a horizontal axis, the coils of which are placed around a prism, the transverse cross-section of which has the shape of a regular polygon having N sides which are of slightly greater length than the sides of the part, the number N being greater than n and preferably incommensurab-is. therewith, in immersing in a bath at least that portion of said spring which contains the part to be treated and in imparting to said spring a rotational movement about its axis or about a line parallel thereto so as to produce the complete reversal of said part and the modification of its zones of contact with the spring.

The expression "long sides" which has been employed above is intended to refer to those sides on which the part can be supported „ In the majority of cases (especially in the case of parts having a cross-section in the shape of a regular polygon), all of the sides must be considered as "long sides". In other instances, and especially in the case in which the part is constituted by a plate having small thickness compared to its width, only two sides of the cross-section out of four must be considered as "long sides".

In order to prevent any lack of uniformity in the surface treatment, it is necessary to ensure that the number N is incommensurate with the number n, thereby preventing any periodicity of contact between the same zones of the part. The easiest method of satisfying this condition is of course to give N a value which is equal to n + 1 although this expedient would only be applicable if the spring were endowed with a continuous movement of rotation which would bring the plate successively against the N sides. On the other hand, if the movement of rotation were reciprocal or, in other words, if the spring were endowed with an alternating motion, the number of contact sides would in that case have to be greater than n„ However, this solution is much less satisfactory than the continuous movement of rotation of the spring by reason of the periodicity which it entails.

A very wide choice of different methods is available for the purpose of driving the spring in rotation; it is possible in particular to make use of a prismatic rod to which the spring is fastened, the said rod having a width of the same order as the length of the side of the polygon. The movement of rotation of said rod initiates the rotation of the spring.

The disadvantage of this solution, however, lies in the fact that it cannot readily be carried into practice when the transverse cross-section of the part to be treated has a small number of long sides n (n = 2 or $). In this instance also, there is a danger that the part will slide instead of rotating, especially by virtue of the fact that the overall size of the rod in addition to that of the part itself makes it necessary to employ a spring having a large diameter and a large number of sides.

One expedient which proves much more satisfactory, especially when the parts to be treated have relatively small dimensions and/or a small number of sides, consists in mounting a plurality of springs in parallel relation on a rotating system which is adapted to rotate about an axis parallel to that of the springs : the rotation of the springs about their axes is then accompanied by a movement of translation along a circle, but this combination of movements does not present any disadvantage.

This invention also has for its object a device for the practical application of the method aforesaid. The device in accordance with the invention comprises, within an electrolytic treatment tank which contains a bath, at least one spring having a horizontal axis, the coils of which are placed around a prism having a transverse cross-section in the shape of a regular polygon with N sides and the lower portion of said spring which contains the part being immersed in said bath, means for driving said spring in rotation about its axis and means for supplying said spring with electric current .

The invention also has for its object by way of novel industrial products the prismatic parts of polygonal transverse cross-sectional configuration which are treated in accordance with the method hereinabove defined.

The invention also consists in other arrangements which are preferably employed in conjunction with the preceding but which can also be employed independently thereof. All of these arrangements will become more readily apparent by perusal of the following description of one mode of application of the invention which is given by way of non-limitative example, reference being had to the accompanying drawings, in which j - Fig. 1 is a view in elevation of a nickel-plating apparatus in accordance with the invention, as ic shown in cross-section along a diametral vertical plane ; - Fig. 2 is a view in the direction of the arrow F of Fig. 1 which shows diagrammatically one of the flanges of the drum and the successive positions which are taken up by the parts to be treated as the drum rotates, said parts being constituted by strips having a flat rectangular cross-section ; - Fig. 3 is a view in perspective of the complete drum ; - Fig. is a diagrammatic detail view showing one of the springs of the drum of Fig. 3 ; - Fig. 5 is an end view of the spring of Fig. 4 and of the strip which is placed therein ; - Fig. 6 which is similar to Fig. 5 shows a spring for the treatment of parts having a square cross-sectional configuration.

The device A in accordance with the invention is disposed during operation in an electrolytic bath 10 contained in a tank, only the bottom 11 of which is shown in Fig. 1. Electrodes which are not shown in the drawings are immersed in the bath 10 which is constituted by a solution of a nickel salt when the operation to be performed on the parts to be treated is a nickel-plating process.

The device A comprises a support frame constituted by two parallel side-plates 12 and 1 which are placed on the bottom 11 of the tank, the side-plate 14 being adapted to carry a motor 16 for driving the device.

The moving portion of the device A is constituted by a drum 18 which is rotatable about a horizo two flanges 20 and 22 carried b a shaft which is carried by roller-bearings 25 mounted in the side-plates 12 and 14. Said roller-bearings are of plastic or metallic material which affords resistance to the corrosive action of the solutions contained in the tank. The flanges 20 and 22 are maintained assembled together by means of a central spacer tube 26 and by means of nuts 28 and 50 which are screwed on threaded portions of the shaft 24, provision being additionally made if necessary for lateral spacer members 51» There are formed at equal angular intervals in the flange 20 recesses 32 which are located in oppositely- facing relation to openings 3 of corresponding shape which are pierced in the flange 22. The recesses 32 are designed to accommodate springs 36 which are inserted through the openings 34 and secured in position by means of a retaining plate 39 which is fixed to the flange 22 by (as shown in Figs 2 ^rf means of screws 40 which engage in the oval4.-&ed holes 41/ and 3) of the plate so as to permit a slight angular displacement of this latter with respect to the flange. Said angular displacement is intended to permit the insertion of the parts to be treated in the springs and to maintain said parts within said springs during treatment as will be explained below.

The springs 36 which are shown and which are intended for the treatment of strips 38 which have a transverse cross-section of flattened rectangular configuration (as shown in Figs. 2 and 5) are made up of three straight wires such as the wire 43 (as shown in Figs. 4 and 5) which delimit the angles of a virtual parallelipiped having a cross-section in the shape of an equilateral triangle and around which are wound the coils of the spring proper „ In order to prevent the direct passage of electric current between the spring 36 and the bath, or rather in order to limit the current transmission zone to that portion of the surface of the coils which comes into contact with the strip to be treated, the wire which constitutes the spring 36 is provided with an insulating covering except on the internal face of the coils. The simplest solution consists in forming the spring of wire which is insulated by a covering of polyvinyl chloride, for example, and in removing this covering within the coils after the spring has been formed „ Electric current can be supplied to the springs in a number of different ways. In the embodiment which is illustrated, the terminal portion of the wire which constitutes the coils of the spring traverses the flange 20 and is clamped between said flange 20 and a nickel ring 2 which is secured to the flange by means of screws „ The ring 42 is supplied with current by means of a conductor 46 terminating in a friction-contact brush or collector-brush 48 which is applied against the ring, as shown in Fig. 1» The other components of the drum and of the frame must of course be insulated„ For this purpose, an acrylic polyester can be employed such as methyl methacrylate so as to form the flange 22 and the retaining plate 39, and another plastic such as polyvinyl chloride can be employed so as to form the shaft 24, the spacer members 26 and 31, the flange 20 and the nuts 28 and „ That portion of the current supply ring 42 which is not in contact with the collector-brush 48 as well as the screws 44 and the metal nuts 49 which serve to secure the spacer members 31 can all be advantageously provided with an insulating covering,, This precaution makes it possible to prevent leakage currents as well as excessive deposition of nickel on the ring 42.

The drum 18 is driven in rotation from the motor 5 16 "by any suitable means such as a driving belt 50 which is passed over pulleys respectively driven by the motor and fixed to the shaft 2 „ The device herein described is intended for the treatment of parts which have a cross-section of flat rectangular configuration, that is to say having two long sides : the coils of the spring are accordingly disposed along a parallelipiped having a triangular cross-section, although other shapes can be envisaged such as a pentagonal cross-section. However, the device is suitable not only for parts of flat rectangular shape but can very easily be adapted to parts having other shapes ; by way of example, Fig„ 6 shows a spring 36 ' having a cross- section in the shape of a regular pentagon for the purpose of treating parts such as the part 38 ' of square cross- 20 sectional configuration.

The operation of the device will now be with J5 / described ija. reference to Figs, 1, 2 and 3 » When the device has been withdrawn from the nickel-plating bath and the current supply is switched off, the drum 18 is loaded with parts to be treated and which consist of strips 38 „ In order to carry out this operation, the screws 40 are slackened off and the retaining plate 39 is moved into the end angular position thereof in which the elongated slots or passageways 52 which are provided in said plate (as 0 shown in Figs, 1 and 3 ) coincide with the openings 34 „ The strips 38 are then inserted through these openings, whereupon the plate 39 is brought back into its locking orientation (as shown in chain-dotted lines in Fig. 2) and locked in positio .by means of screws 40 „ Recessed portions 56 of suitable shape (as shown in Figs. 2 and 3 ) which are formed in the plate 39 can also permit the insertion of nuts for securing the spacer members 31 .

Once the drum has been loaded, the device is introduced successively in each of the degreasing, pickling and washing baths, then in the electrolytic coating bath (as shown in Fig. l). The drum is set in rotation by means of the motor 16 and an electric supply voltage is applied between the springs 36 and electrodes which are placed in the bath, the springs being connected to the negative pole . During the rotation of the drum in the direction shown by the arrow f in Fig. 2, the strips 38 are subjected to a periodic "flip-over" motion (arrow f' ) which ensures uniform nickel-plating over their entire surface. It is apparent in particular that each strip 38 has an orientation which is opposite to its initial orientation after one full revolution of the drum, any lack of uniformity being consequently avoided.

By way of example, it can be noted that a device which is constructed for the purpose of nickel-plating uranium strips measuring 15 mm x 3 mm in transverse cross-section and approximately 60 mm in length comprises a drum 180 mm in diameter which carries twelve springs of substantially triangular cross-section and formed of nickel wires 1 mm in diameter. The small plates which are introduced within the springs are subjected to a treatment involving suitable surface preparation and washing followed by a nickel-plating process during which the drum rotates at a speed of 10 rpm.

The device which has just been described and the process which entails the utilization of said device are in no way limited to the metallic coating of parts and are applicable to any operation involving bath treatment 5 the term "bath treatment" is used here in a wide sense and includes within its scope such treatments as pickling, degreasing, washing, passivation and so forth which can either precede or follow the electrolytic coating process.

It will be readily understood that the invention is not limited in any sense to the single embodiment which has been illustrated and described and it must be understood that the scope of this patent extends to all alternative forms or all or a part of the arrangements described which remain within the definition of equivalent means .

Claims (10)

HAVING- NOW particularly described and ascertained the nature of our said invention and in what manner the same is to

1. A method of electrolytic and/or chemical surface treatment of prismatic parts each having in transverse cross-section n long sides of substantially equal length, said method consisting in supporting the 5 part to "be treated on the lower portion of a coiled spring having a horizontal axis, the coils of which are placed around a prism having a transverse cross-section in the shape of a regular polygon with N sides which are of slightly greater length than said long sides of each part, 0 the number being greater than n and preferably j?, incommensurate therewith, in immersing in the bath at least that portion of said spring which contains the part to be treated, in imparting to said spring a continuous movement of rotation about its axis so as to initiate the 5 periodic reversal of said part and the modification of its zones of contact with the spring, and also to establish a potential difference between said bath and said part „

2. „ A method in accordance with Claim 1, wherein the number N of sides of the spring is equal to n + 1.

3. , A device for the application of the method in accordance with Claim 1 and comprising, within an electrolytic and/or chemical treatment tank which contains the bath, at least one spring having a horizontal axis and 5 the coils of which are placed around a prism having a transverse cross-section in the shape of a regular polygon with sides and the lower portion of said spring which contains the part being immersed in said bath, means for driving said spring in rotation about its axis or along a 0 line parallel to said axis and means for supplying said spring with electric current .

4. A device in accordance with Claim 3, comprising a plurality of springs which are fixed at uniform angular intervals about the axis of a drum having a horizontal axis, said driving means being adapted to initiate the rotation of the drum.,

5. A device in accordance with Claim 4, wherein said drum is partially immersed in the electrolytic bath and wherein the means for supplying electric current comprise an electrically conductive ring which is integral with the peripheral portion of the drum and connected to each spring and a collector-brush placed outside the bath and in sliding electrical contact with said ring.

6. A device in accordance with Claim 4, wherein the drum comprises two flanges of insulating material which are maintained assembled together by means of spacer members, one of the flanges being adapted to carry said ring and being provided with recesses for receiving the terminal portions of the springs, the other flange being pierced by slots through which the springs are inserted and which are located opposite to said recesses, and comprises a plate for retaining the springs and fixed to the second flange.

7. A device in accordance with Claim 6, wherein said retaining plate is fixed to the corresponding flange by connecting means which permit an angular displacement of the plate between a first position in which it permits the insertion of parts to be treated in the springs through openings provided therein and a second position in which said plate imprisons the parts in said springs.

8. A prismatic part as treated by application of the method claimed in Claim 1 or Claim 2. 9o A method of surface treatment as defined in

9. Claim 1, substantially as hereinbefore described.

10. A device for the practical application of said method, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings „ B 17 5 - 3