Method for treating surfaces of geometrically complex parts, part-carrying device and treatment device

Abstract

A part-carrier for electrolytically treating geometrically complex parts includes a reinforcement vertically supporting supports that are movable in rotation and designed to carry the parts to be treated, and a control member which, when activated, pivots the movable supports in sequence to either side of a neutral initial position. Application to electroplating.

Claims

1. A method for electrolytic or anodic oxidation surface treatment comprising the positioning in a neutral initial position, by means of a removable part-carrier, geometrically complex parts constituting a first electrode, in a treatment bath contained in a tank including one second electrode of polarity opposite to that of the first electrode, the geometrically complex parts made of metal or metallizable plastic material, wherein: a) the geometrically complex parts are such that, in a neutral initial position at 0 degree; and b) during the treatment of the geometrically complex parts, the geometrically complex parts are subjected to sequential rotations on either side of their neutral initial position by an angle up to 90 degrees, so as to increase the exposure to lines of current established between the first and the second electrode during the implementation of the treatment method; wherein the geometrically complex parts to be treated are held in different angular positions resulting from the sequential rotations during a determined time as a function of the treatment and of the geometric complexity of the parts.

2. The method of claim 1, wherein the angle of rotation of the geometrically complex parts is of 45 degrees on either side of the neutral initial position.

Description

(1) The following description in relation with the appended drawings, given by way of non-limitative examples, will allow a good understanding of what the invention is consisted in and how it may be implemented.

(2) The following of the description refers to the appended figures, in which:

(3) FIGS. 1A to 10 are schematic representations of the impact of the lines on the surfaces of a geometrically complex part as a function of the orientation thereof;

(4) FIG. 2 is a perspective view of an embodiment of a part-carrier according to the invention in its neutral initial position;

(5) FIGS. 2A and 2B are face and top views, respectively, of the part-carrier of FIG. 1;

(6) FIG. 3 is a perspective view of the part-carrier of FIG. 1, after a rotation by 45 in the clockwise direction with respect to the neutral initial position;

(7) FIGS. 3A and 3B are face and top views, respectively, of the part-carrier of FIG. 3;

(8) FIGS. 4A and 4B are face and top views, respectively, of the part-carrier of FIG. 1, after a rotation by 45 in the anticlockwise direction with respect to the neutral initial position;

(9) FIG. 5 is a schematic perspective view of the part-carrier of FIG. 1 placed in a treatment tank;

(10) FIG. 6 is a top view of the part-carrier and of the treatment tank of FIG. 5, with the parts to be treated in their neutral initial position with respect to the anodes;

(11) FIGS. 7 and 8 are top views similar to FIG. 6, after rotation by 45 of the parts to be treated, on either side, respectively, of the neutral initial position;

(12) FIGS. 9 to 10 are schematic top and perspective views, respectively, of an embodiment of the part-carriers and of a treatment tank according to the invention, the part-carrier being taken out of the tank.

(13) FIGS. 2, 2A and 2B show a face and top perspective view, respectively, of an embodiment of a part-carrier 1 according to the invention.

(14) The part-carrier 1 comprises a generally rectangular reinforcement 2, made of an electrically conductive material, including an upper side 2a, a lower side 2b and two lateral sides 2c.

(15) Part-carriers also called bar stands 3, also made of an electrically conductive material, arranged parallel to the lateral sides 2c of the reinforcement 2, are held between the upper side 2a and the lower side 2b of the reinforcement 2 so as to be able to turn about a vertical axis on either side of a neutral initial position as shown in FIG. 2. This rotatable holding may be made by means of bearings 4, for example plain bearings, integral with the upper 2a and lower 2b sides of the reinforcement 2. Means 5 for fastening the parts 6, for example clamps, clips or springs, are arranged along the supports. In the represented embodiment, the part fastening means 5 are arranged along supports 3 so as to hold the parts 6 by opposite pairs. Of course, other arrangements of fastening means 5, for example staggered arrangement, are conceivable as a function of the geometry of the parts to be treated and of the contemplated treatments.

(16) The upper end of each of the rotary supports 3 is provided with a pinion 7 that engages with a rack 8 integral with the upper side 2a of the reinforcement 2. An end of the rack 8 is integral with an operating arm 9, whose free end may be removably connected to the control rod 11 of a linear actuator 10 such as a cylinder.

(17) A horizontal translation of the rack 8, a one direction or the other, makes the supports 3, and as the result the parts 6, rotate on either side of the neutral initial position.

(18) Of course, the control of the rotation of the supports 3 and hence of the parts 6 could be made by other means such as a cam system, or an endless screw system.

(19) The upper side 2a of the reinforcement is a bar ensuring the holding of the reinforcement 2 in the treatment tank and the supply of current to the rotary supports 3.

(20) As well known, the reinforcement 2, the supports 3 and the part fastening means 5 are made of an electrically conductive material and form together an electrode, in particular the cathode of a device for electrolytic or anodic oxidation treatment, in particular electroplating, and means are provided, generally on the upper side 2a by the connection to a source of current.

(21) By way of illustration, FIGS. 3, 3A and 3B show in perspective, face and top view, respectively, after a rotation of the supports 3 by 45 in the clockwise direction, and FIGS. 4A and 4B show a face and top view, after a rotation by 45 in the anticlockwise direction, the positioning of the parts to be treated with respect to the neutral initial position of FIG. 2. The parts to be treated hence undergo a rotation along an arc of a circle and that is oscillatory.

(22) The part-carrier 1 according to the invention is particularly designed to be used in a device for electrolytic and anodic oxidation treatment, in particular electroplating, and the implementation of the method of the invention.

(23) With reference to FIGS. 5 to 10, we will now describe an embodiment of a treatment device according to the invention, as well as the implementation of the method of the invention.

(24) FIG. 5 shows the part-carrier 1 of the invention, placed in a treatment tank 20 of a device according to the invention. As shown in FIG. 5, the treatment tank 20 is of generally parallelepipedal shape.

(25) The tank 20 comprises an open upper face 20a, a bottom 20b and two pairs of opposite lateral walls, a main pair 20c, 20d and a secondary pair 20e, 20f.

(26) A set of electrodes 21a, 21b, typically anodes, is arranged vertically along each of the opposite main lateral walls 20c, 20d, and are for example in the form of vertical and parallel rectangular electrically conductive bands,

(27) The part-carrier 1 is arranged and held vertically in the tank 20 between the sets of electrodes 21a, 21b, the ends of the upper side 2a of the reinforcement 2 bearing on the upper edges of the secondary lateral walls 20e, 20f, the supports 3 being then arranged vertically opposite the sets of electrodes 21a, 21b, in particular on each of the bands constituting the sets of electrodes.

(28) A linear actuator 10 is fixed on the upper edge of a secondary lateral wall 20e and is removably connected by its control rod 11 to the operation arm 9 of the rack 8.

(29) FIGS. 9 and 10 are face and perspective views of a treatment device according to the invention, with the part-carrier 1 out of the treatment tank 20, before or after a treatment. In this embodiment, the linear actuator 10 remains on the tank 20 with disengagement of the operation arm 9 of the rack 8.

(30) Of course, the device according to the invention may include several successive tanks as described hereinabove, for different successive treatments of the parts 6 carried by a same part-carrier 1.

(31) If, in the embodiment of the device described hereinabove, it is provided an actuator 10 fixed on each treatment tank, it is possible, as a variant, to provide a single actuator fixed to the upper rod 2a of the reinforcement 2 of the part-carrier 1, this actuator being then transported from tank to tank in the same time as the part-carrier.

(32) An implementation of the method of the invention will now be described in connection with FIGS. 5 to 10 and within the framework of an electrolytic treatment.

(33) As shown in FIGS. 5 and 6, the part-carriers 1 described hereinabove, with the geometrically complex parts 6 to be treated arranged on the rotary supports 3, is placed vertically in a treatment tank 20 containing an electrolyte bath, between the sets of anodes 21a and 21b, the upper rod 20c of the reinforcement 2 bearing on the opposite sides of the open upper surface 20a constituting the upper edges of the secondary lateral surfaces 20e, 20f of the tank 20, not provided with anodes. The rod 2a is connected to a source of current, for example by means of a conductive braid or contact V-blocks (not shown). The rotary supports 3 are electrically connected to the rod 2a by means of conductive braids (not shown).

(34) In operation, the reinforcement 2 and the parts 6 form a cathode opposite the sets of anodes 21a and 21b.

(35) The rack 8 is connected through the operation arm 9 to the rod 11 of a linear actuator 10, for example a cylinder, fixed to the upper edge of the secondary lateral surface 20e of the tank 20.

(36) At this step, the supports 3, and then the parts to be treated 6, are in a neutral initial position in which the surfaces a of the parts 6 are directly opposite the anodes 21a, 21b and are directly impacted by the lines of current L established between the anodes and the cathode during the treatment. On the other hand, the surfaces b and c of the parts 6 that are not opposite the anodes 21a, 21b, are a little or not impacted by the lines of current L.

(37) During the treatment, the linear actuator 10 is sequentially activated.

(38) In the implementation shown, the linear actuator 10 is activated a first time to make the rod 11 move rearward and hence perform a translation to the right of the rack 8. This translation to the right of the rack 8 has for effect to make the supports 3 pivot in the clockwise direction, herein by an angle of 45 with respect to the neutral initial position.

(39) After this rotation of the supports 3, the exposure of the surfaces b of the parts 6 to the anodes is increased and the impact of the lines of current on theses surfaces is increased (FIG. 7).

(40) The linear actuator 10 is then activated a second times to make the rod 11 move forward and hence perform a translation to the left of the rack 8. This translation to the left of the rack 8 has for effect to make the supports 3 pivot in the anticlockwise direction, herein by an angle of 45 with respect to the neutral initial position.

(41) After this rotation of the supports 3, the exposure of the surfaces c of the parts 6 to the anodes is increased and the impact of the lines of current L on theses surfaces c is increased.

(42) Of course, according to the treatment and the complexity of the part geometry (FIG. 8), it may be used during the treatment several rotations by an angle comprised between 0 degree (neutral initial position) and 90 on either side of the neutral initial position.

(43) Likewise, the time of holding at each of the chosen positions will depend on the treatment and of the geometrical complexity of the parts.

(44) In the case of an electroplated coating, the rotation angles and the time of holding at the different angular positions will be chosen so as to obtain the most homogeneous possible coating, and in particular of thickness the most equal possible.

(45) The sequence of rotations during a treatment may be controlled automatically by a computer program.

(46) At the end of the treatment, the operating arm 9 is locked at the neutral position and is disconnected from the rod 11 of the actuator and the upper rod 2a is disconnected. The part-carrier 1, with the parts 6 to be treated, is then removed from the tank 20, the actuator 10 remaining fixed to the tank 20.

(47) The part-carrier 1, with the parts 6, may then be placed in another treatment enclosure for another electrolytic treatment or another treatment, for example drying, curing, etc., or the parts 6 may be dismounted from the part-carrier 1 and stored before shipping.