MXPA97005995A - Apparatus and method for selective coating departments of me - Google Patents

Abstract

The present invention relates to an apparatus for simultaneously generating an electrolytic coating in a first surface portion of each of at least two electrically conductive workpieces, the apparatus is characterized in that it comprises: an electrocoating tank having an interior and including a wall having at least two apertures formed hollowed to receive the work pieces, one of the work pieces, one of the openings, the tank further includes at least one electrode extending to the high liner tank and a discharge; to temporarily hold the work pieces in the openings to place their first surface portions in fluid communication with the interior of the tank, a seal for the openings with respect to the work pieces when the work pieces are clamped there, so that only the first surface portion of the work pieces are placed in fluid communication with the i nterior of the electrocoating tank, means for directing an electrolyte to the tank, in such a way that the electrolyte bridges each of the work pieces and at least one electrode, and a power supply connected to the work pieces and at least one electrode , respectively, to apply a current through the electrolyte in the tank when the electrolyte bridges the work pieces and at least one electrode, thereby generating an electrolytic coating in the first surface portion of each of the work pieces; the means for directing a rinsing fluid to the tank, for rinsing the first surface portion of each of the work pieces

Description

APPARATUS AND METHOD FOR SELECTIVE COATING OF METAL PARTS BACKGROUND OF THE INVENTION The present invention is generally related to apparatuses and methods for the selective coating of metal parts using an electrolytic deposition method as it may be advantageous for anodizing hard coating for heads of aluminum pistons that are used in an internal combustion engine. More specifically, the invention relates to apparatuses and methods for the continuous processing of these metallic parts with minimal handling to obtain coatings of superior quality and consistency while simultaneously reducing their relative cost. Known processes for the selective coating of metal parts such as aluminum piston heads, generally include a series of synchronized dives in one or more baths of appropriate cleaning, etching, coating and / or rinsing solutions to generate the desired coating of a single or multiple layers. Equipment for handling complex materials is required to achieve these sequential dives, which includes equipment to transport supports that contain multiple work pieces between each bath, and to lower the supports in each bath for a predetermined period of time. In this way a large physical plant is required to house both the material handling equipment and the necessary processing baths, involving substantial capital investment. While some processes to produce multi-layer coatings can reduce the number of physical "dips" required as through light or a single bath containing a "mixed" electro-coating solution combined with anodic and cathodic alternating coating steps , as illustrated in the US Patent No. 3,556,958 issued to Hutchings et al., However there remains a substantial need for the handling of individual work pieces and / or supports during these processes. This handling in turn can adversely impact the quality and overall consistency of the resulting coating while additionally increasing its relative cost both in terms of increased coating times and equipment / capital requirements. Undoubtedly, in the event that only a portion of the work piece is to be coated, as when only a coating on the head of a piston is sought, an additional substantial expense is found when those areas that are to remain unmasked are unmasked. free of coating with even greater complications in the handling of masked workpieces.

Another problem encountered with known methods for coating metal parts is found in the fact that many of the solutions employed must be maintained at temperatures other than room temperature. For example, it is well known that the optimum temperature of the sulfuric acid electrolyte used in the hard anodizing of 6000 series aluminum alloys is 0 ± 1 ° C (32 ± 2 ° F) with the parts that are probably submerged subsequently in water hot that is maintained at a temperature of at least 95 ° C (200 ° F) probably for 15 minutes in order to hydrate / seal the resulting aluminum oxide coating. Similarly, the nominal temperature of a chromic acid electrolyte bath is preferably 100 plus minus 37 ± 5 ° C (9 ° F). Given the open processing tanks typical of these known coating methods, a large amount of energy must be spent to heat or cool their various solutions to the proper temperature. The latent heat of dimensionally sized supports and other material handling equipment used in connection with those methods must also be factored into the energy equation, as well as the larger processing tanks and larger quantities of solutions required to accommodate this handling equipment of parts. Even moreThese known coating methods inherently present certain safety problems for workers and the environment. In particular, the use by these methods of open processing baths exposes workers to vapors generated either by the solutions themselves or as a by-product of electrolysis, with the intensity of the vapors almost certainly increased through the necessary agitation of every bathroom And since the processing baths must remain open for substantial periods to accommodate the parts management team, there is little opportunity to recover these vapors and therefore further damage to the environment. Accordingly, what is required is a semi-automatic method for the selective coating of metallic parts such as pistons, which avoids the aforementioned problems to provide a single or multiple layer coating with superior quality and consistency, preference at lower cost. SUMMARY OF THE INVENTION An object of the invention is to provide an apparatus and method for the selective coating of metal parts that characterize a reduced handling of these metal parts. Another object of the invention is to provide an apparatus and method for the selective coating of metal parts that reduces or otherwise eliminates the requirements for masking.

Another object of the invention is to provide an apparatus and method for the selective coating of metal parts that require reduced floor space. Another object of the invention is to provide an apparatus and method for the selective coating of metallic parts that require smaller amounts of the various processing solutions. Another object of the invention is to provide an apparatus and method for the selective coating of metal parts that require lower amounts of energy. A further object of the invention is to provide an apparatus and method for the selective coating of metal parts, which characterizes reduced worker exposure to the various solutions employed there and particularly to the electrolysis by-products. Still another object of the invention is to provide an apparatus and method for the selective coating of metal parts that maintains its various processing solutions and performs each of its processing steps in sealed containers, thereby promoting increased environmental safety while reduce energy requirements and evaporative losses. Under the invention, an apparatus for selectively coating a first surface portion of an electrically conductive workpiece includes an electrocoating tank, wherein the electrocoating tank includes a wall having an opening therein formed, adapted to receive the workpiece; an electrode that extends to the electrocoating tank and a discharge. The apparatus further includes means for temporarily securing the workpiece in the opening, in order to place the first surface portion of the workpiece in fluid communication with the interior of the electrocoating tank and a seal disposed in the opening to seal the workpiece. opening relative to the workpiece when the workpiece is clamped, such that only the first surface portion of the workpiece is placed in fluid communication with the interior of the electrocoating tank. More specifically, in a preferred embodiment of the apparatus, the means for temporarily holding the workpiece in the opening include an accessory adapted to receive the workpiece and an actuator mounted in the electro-coating tank for transferring the fitting relative to the opening. The actuator in this manner operates to controllably insert and hold the workpiece within the opening. For example, when the workpiece is a piston whose head is only to be coated in accordance with the invention, the accessory preferably includes a post that functions in a manner very similar to a pin for retaining the piston there. The fixture will also preferably include a frame to support the piston in order to prevent its rotation relative to the post. And in a preferred embodiment, the actuator also operates to rotate the fitting relative to the tank to facilitate placement of the workpiece in the fitting. In accordance with the present invention, the apparatus further includes a means for directing an electrolyte within the electrocoating tank, such that the electrolyte bridges the workpiece and the electrode; and a power supply connected to the workpiece and the electrode respectively to apply a current through the electrolyte in the electrocoating tank when the electrolyte bridges the workpiece and electrode, whereby an electrolytic coating is generated in the first surface portion of the work piece. The apparatus also includes a means for directing a flushing fluid to the electrocoating tank for rinsing the first surface portion of the workpiece, whereby any remaining electrolyte is removed from the workpiece. According to another additional feature of the present invention, the means for directing the electrolyte to the electrocoating tank preferably includes a spray nozzle positioned within the centralized tank opposite the first surface portion of the workpiece when the workpiece is fastened to the opening. The centralized spray nozzle and its fluid manifold is preferably additionally formed of an electrically conductive material such that it can be used as an electrode (cathode) of the electrolytic cell formed when the workpiece (of the anode of the cell) is attached to the opening of the electrocoating tank and the electrolyte is directed to the electrocoating tank. Means for directing the electrolyte to the electrocoating tank preferably also include a storage tank for storing an electrolyte supply, a supply conduit extending from the storage tank of the electrocoating tank, an operational pump to the stored pump electrolyte. in the storage tank through the supply conduit to the electrocoating tank and a first return conduit extending from the discharge of the electrocoating tank to the storage tank. The electrolyte can thus be circulated between the electrocoating tank and the storage tank, thereby reducing the amount of electrolyte required under the present invention. In the proportion that other processing solutions are to be directed to the electrocoating tank, either before or after the electrolyte in order to obtain the desired coating, those other solutions are likewise kept in discrete storage tanks that are to be circulated through the electrocoating tank through additional ducts (while preferably sharing the same spray nozzles). In that regard, it is noted that the rinsing fluid, typically tap water directed to the electrocoating tank through the spray nozzles after a processing solution is discharged, will preferably not be recirculated. In contrast, this rinsing fluid is preferably discharged from the electrocoating tank and supplied by a separate conduit directly to the suitable waste water treatment equipment. And according to yet another feature of the present invention, the storage tanks and conduits are insulated to maintain the electrolyte and any other solutions that are different from the ambient temperature at their optimum temperatures, for example 0 ± 1 ° C (32 ± 2ßF) for the electrolyte of sulfuric acid used for the anodizing of hard coating of aluminum alloys. Since the electrolyte and other heated / cooled solutions circulate through the electrocoating tank itself are kept in small insulated storage tanks, instead of the open processing tanks so typical of prior art methods, the energy requirements of the present apparatus and method, are markedly reduced. As an added benefit of this circulation, the temperatures of the circulated solutions - particularly those of the electrolyte as sprayed from the nozzles to the workpiece - can be markedly regulated with an accompanying increase in coating quality and consistency. Finally, under the present invention, the electro-coating tank is preferably completely closed or sealed; and a second return conduit connected to the electrocoating tank at a point above the normal operating temperature of the electrolyte extends from the electrocoating tank to the storage tank. In addition to performing the function of an overflow return, the second return conduit serves to vent the electrolysis by-products, particularly the hydrogen gas thus generated, back to the storage tank either for recovery or for final disposal. In this way, the electro-coating tank remains sealed to protect workers against the vapors generated by the coating process. From the foregoing, it will be appreciated that according to the present invention, an electrically conductive workpiece is clamped in an opening extending through a wall of an electrocoating tank or otherwise adapted to sealingly engage the workpiece. of work so that only a desired surface portion of the work piece is placed in fluid communication with the interior of the electrocoating tank. With the electro-coating tank thus sealed, a pre-electrolyte treatment fluid can first be directed into and then discharged from the electrocoating tank. Examples of these pre-electrolyte treatment fluids include without limitation known cleaning solutions, caustic etching, deoxidizing solutions, activating solutions and waters. Undoubtedly, a purge or flushing fluid such as tap water is preferably directed into and substantially discharged from the electrocoating tank immediately prior to the introduction of an electrolyte. The electrolyte is thus directed towards the electrocoating tank, preferably through a spray nozzle in such a manner that the electrolyte is sprayed onto the exposed surface portion of the workpiece. With the electrolyte that bridges both the workpiece and the electrode located inside the electrocoating tank (this electrode preferably comprises the same nozzle and manifold used to spray the electrolyte on the surface of the workpiece) a current is applied to the electrolyte to generate an electrolytic coating and the exposed surface of the anodic workpiece. As noted above when describing a preferred apparatus according to the present invention, the electrolyte is preferably circulated between the electrocoating tank and an insulated storage tank for spraying only "fresh" electrolyte, ie, electrolyte free of bubbles. desired temperature and composition on the surface of the work piece during application of the current. In this way, a coating of superior quality and consistency is obtained. In a preferred method, the electrocoating tank is vented during electrolysis to a remote location for recovery or disposal of the gas and heat byproducts generated in that manner. Once the desired coating has been generated, the current is removed, the electrolyte flow to the electro-coating tank is stopped and the electrocoating tank is discharged from the electrolyte. A rinse fluid such as tap water or another neutralizing solution is subsequently directed to the electrocoating tank, preferably through the same spray nozzles used to spray electrolyte and electrolyte pre-treatment fluids on the exposed surface of the workpiece. job. In this way, any remaining electrolyte is removed from the workpiece. After the flushing fluid is completely discharged from the electrocoating tank, any desired post-electrolyte treatment fluid can similarly be directed into and subsequently discharged from the electrocoating tank, possibly with a further flushing of the electrocoating tank in the manner described above. Examples of suitable post-electrolyte treatment fluids include, without limitation, a sealant such as hot water, steam or sodium dichromate.; a solution containing a colorant; and a solution containing a dry lubricant such as polytetrafluoroethylene (PTFE or "Teflon" * ".) In a preferred method of practicing the invention, wherein the coated surface is below ambient temperature after final rinsing, the heated air It is circulated through the tank to raise the temperature of the coated surface and therefore prevent further condensation of ambient moisture from the workpiece by removing the workpiece from the opening.The workpiece is subsequently removed from the opening to complete its processing BRIEF RIPTION OF THE DRAWINGS With reference to the drawings, in which like reference numerals are used to gnate similar elements in each of the various figures, Figure 1 is a schematic illustration of a preferred apparatus for cleaning, activate, anodize for hard coating and rinse the heads of several aluminum pistons simultaneously according to on the present invention (for clarity illustrated without the means for holding each piston in its respective opening in the electro-coating tank); Figure 2 is a perspective, partly exploded view of an electrocoating tank constructed in accordance with the invention for use in hard coating anodizing simultaneously of the aluminum multi-piston heads, including an actuator / accessory operated by cam (for inserting and releasably securing the pistons in the corresponding openings formed in the front wall of the tank, and a supply conduit extending inside the tank having integral spray nozzles placed thereon in order to be in opposition to the heads of the tank. piston, where they are fastened in the openings; Figure 3 is a longitudinal view partly in cross section of the cam operated actuator / actuator illustrated in Figure 2 on the line 3-3, with the fittings being moved and rotated away from the opening to facilitate placement of its pistons; Figure 4 is a first cross-sectional view of the aperture; of the electrocoating tank, actuator / accessory operated by cam and opposite spray nozzle of Figure 2 on line 4-4, with the piston moving and rotating away from the opening, to facilitate its placement in the fitting, and in addition with the stop pin / sleeve bearing assembly at the close end of the superposed actuator, but without the accessory support frame. Figure 5 is a second cross-sectional view of the electro-coating tank opening, accessory / cam operated actuator and opposite spray nozzle of Figure 2 similar to that of Figure 4, but with the piston rotated in alignment with the opening and also moved so as to be partially inserted in the opening; Figure 6 is a third cross-sectional view of the electro-coating tank opening, accessory / cam-operated actuator and opposite spray nozzle of Figure 2 similar to that of Figure 4, but with the piston rotated in alignment with the opening and furthermore being moved to fully insert in the opening, thus axially compressing the toric ring seated within the opening to seal the opening; Figure 7 is a detailed perspective view of the inner sleeve cam / bearing plate, inner shaft, outer shaft, stop pin and cam comprising a close end of a cam operated actuator as seen in Figure 2; and Figure 8 is a second partial cross sectional detail view of the cam plate / guide bearing, bypass spring and cam comprising the near end of a cam operated actuator illustrated in Figure 2 and particularly on line 8. -8 of Figure 3. DESCRIPTION r > KTAT.T.?DA OF PREFERRED MODALITY A preferred apparatus 10 for cleaning, deoxidizing, anodizing with hard coating and sealing the head of each of several aluminum pistons 12 simultaneously in accordance with the present invention is illustrated schematically in Figure 1 .

Specifically, the apparatus 10 includes a sealed electrocoating tank 14, a detailed view of which is illustrated in Figure 2. The electrocoating tank 14 which is preferably formed of an electrically non-conductive and thermally insulating material such as ABS plastic, is nominally provided with the bottom discharge 16 and a vapor / overflow return 18. The electrocoating tank 14 also has a plurality of cylindrical openings 20 formed in its front wall 22. Each opening 20 is adapted to receive an individual piston 12 inserted therein. longitudinally. As more fully described below in connection with Figures 4 to 6, an O-ring seal 24 is disposed within each opening 20 to effect a seal with respect to each piston 12 when the piston 12 is inserted and subsequently fastened to the piston 12. opening 20 by appropriate fastening means 26 (fastening means 26 are described below in connection with Figures 2-8). Going back to Figure 1, the apparatus 10 further includes several external storage tanks 28, 30, 32 and 34 which contain a variety of solutiemployed in a preferred method for generating an anodized surface of hard coating on the head of each piston 12. For example, the first storage tank 28 is illustrated to contain an aqueous cleaning agent; the second storage tank 30 a commercial deoxidizer comprising nitric acid; the third storage tank 32, a solution of sulfuric acid (H2SO4) in a specified temperature range, for example, probably at 0 ± 1 ° C (32 ± 2 ° F) (hereinafter "the electrolyte"); and the fourth storage tank 34, hot water maintained above 95 ° C (200 ° F) for use as a sealant. A source (not shown) of pressurized water at room temperature ("tap water") is also provided, as a source of compressed cold or hot air (not shown). It is noted that storage tanks 32, 34 for electrolyte and hot water are preferably insulated to reduce energy requirements and otherwise individually heated / cooled as required. The precise formulation of the solutions contained within the storage tanks 28, 30, 32 and 34 will be known to those skilled in electrocoating techniques. It will be appreciated, however, that the solutions described above are simply exemplary; other solutions suitable for use in the apparatus 10 include, without limitation, various rinsing and neutralizing solutions; Ordered caustics; other electrolytes, other sealing solutions, for example steam or sodium dichromate; solutions containing a colorant to impart a desired color to the coating; and solutions containing a dry film lubricant such as "Teflon MR", to make the coating "self-lubricating". The particular solutions and the order and manner in which they are introduced to the electrocoating tank 14 will be chosen in a manner known to those skilled in electrocoating techniques in order to achieve a particular coating on a given workpiece with specific hardness, resistance, porosity / density, resistance to wear, lubricity and / or color. A fluid supply network itself comprises the dedicated pumps 36 and the control valves 38, which connect each storage tank 28, 30, 32, 34 and the source of running water to the electrocoating tank 14 through a duct 40. One end 42 of the supply conduit projects into the electrocoating tank 14. That end 42 of the supply conduit 40 is further provided with a plurality of integral spray nozzles 44 positioned within the electrocoating tank 14 as opposed to the openings 20 formed in its front wall 22. In this way, a given solution pumped from its respective storage tank 28, 30, 32, 34 (as well as running water rinsing) can be directed to the electrocoating tank 14 and sprayed directly on the heads of the pistons 12 fastened in the openings 20. A network of return ducts 46 and control valves 48 connects the discharge of an electrocoating tank 16 and vapor return / overflow 18, either to one of the storage tanks 28, 30, 32, 34 or to a suitable waste treatment equipment (not shown). As seen in Figure 1, the apparatus 10 includes a rectifier 50 for supplying current to the electrolytic cell created, while the pistons 12 are clamped to the openings of the electrocoating tank 20 and the electrolyte from the third storage tank 32 is directed to the electrocoating tank 14 (whereby the pistons 12 form the anode of the electrolytic cell). More specifically, in the preferred embodiment, the end 42 of the supply conduit 40 projecting to the electro-coating tank 14, is preferably formed of a non-reactive, electrically conductive material such as stainless steel, so that it can be used as a electrode (cathode) during electrolysis, obviating the need for a separate electrode. Accordingly, the negative terminal of the rectifier 50 is connected to that end 42 of the supply conduit 40. The positive terminal of the rectifier 50 is connected to the piston 12 when it is clamped to the opening of the electrocoating tank 20 (for reasons of clarity, the positive terminal of the rectifier 50 is shown connected only to one of the pistons 12). Again with reference to the detailed view of the electrocoating tank 14 illustrated in Figure 2, the electrical terminals 52 are illustrated to extend inside the electrocoating tank 14 from the end 42 of the supply conduit 40 to a first set of electrical terminals 54 located on one of the outer walls of the electro-coating tank. These terminals 54 in turn are connected to the negative terminal of the rectifier 50. A second set of electrical terminals 56 is provided in the actuators 26 to be connected to the positive terminal of the rectifier 50. The means 26 for inserting and holding each piston 12 in their respective aperture 20 includes a plurality of actuators 58 mounted on the front wall 22 of the electrocoating tank 14, and a plurality of accessories 60 supported by the actuators 58. Each accessory 60 is adapted to receive one of the pistons 12 whose head 62 is will anodize with hard coating in the electrocoating tank 14. Each actuator 58 is operative to both move and rotate the accessory 60 (and the piston 12e) relative to the opening 20. The openings 20 and their corresponding accessories 60, preferably are They are arranged in rows to allow the use of a common actuator 58 for each row of accessory 60 and openings 20. Actuators 58 and their s associated accessories 60 are illustrated in greater detail in Figures 3 to 8. Each of the actuators 58 includes an elongated reinforcing base plate 64 fastened to the front of the front wall of the electrocoating tank 22.; and at least two guide bearings 66, 68 mounted longitudinally on the base plate 64 to be placed on opposite sides of the at least one opening 20. Each guide bearing 66, 68 has an elongated slot 70 extending in a direction generally parallel to the axis of the cylindrical openings 20. One of the guide bearings 68 for a particular actuator 58 has a sleeve bearing 72 located within its slot 70. The sleeve bearing 72 is adapted to receive a first arrow 74 stamped there (below "inner arrow"). 74"). A first radially extending stop pin 76 on the inner shaft 74 couples an enlarged circumferential groove 78 formed in a longitudinal end 80 of the sleeve bearing 72 to limit the amount of relative rotation of the inner arrow 74. A spring 82 located within from the slot 70 the sleeve bearing 72 (and the inner arrow 74 that transports) drifts away from the base plate 64 to a first end 84 of the slot 70. The inner arrow 74 is preferably formed of an electrically conductive material such as stainless steel in such a way that it can be connected to the positive terminal of the rectifier 50 and therefore conduct current to the piston 12. The other of the guide bearings 68 for this particular actuator 58 is adapted to receive a second arrow of larger diameter 86 ( then "outer arrow 86") @ k sleeved with respect to the remaining section of the inner arrow 74. Additional springs 82 located within the rails nuras 70 of these other guide bearings 68, similarly derive the outer arrow 86 (and inner arrow 74 inside) away from the base plate 64 of the first end 84 of their grooves 70, respectively. At least one cam 88 is transported by the outer shaft 86 proximate each of the guide bearings 66, 68. Each eccentric cam surface engages a complementary cam plate 90 connected to each guide bearing 66, 68 in such a way that turning the outer arrow 86, the cams 88 operate to move the arrows 74, 86 within the guide bearings 66, 68 away from their first ends 84 and towards the front wall 22 of the electrocoating tank 14. In that aspect, it is noted that the outer arrows 86 are illustrated as being manually rotated by means of a lever 92 extending radially from the outer shaft 86 at its free end 94. It will be appreciated, however, that the inner shaft 74 can be moved by any suitable device for imparting rotary motion. controlled to an arrow, such as a stepped motor (not shown) thus facilitating system automation. A second radially extending stop pin 96 on the inner arrow 74 extends through an enlarged circumferential groove 98 formed in the outer arrow 86. The outer arrow 86 is thus free to rotate relative to the inner arrow 74 within of a pre-determined range, after which the second stop pin 96 engages one or the other of the circumferential ends of the slot, to prevent further rotation of the outer arrow 86 relative to the inner arrow 74. In this way, the inner arrow 74 is selectively displaced by the outer arrow 86. As seen in Figures 3 to 6, the inner arrow 74 of each of the actuators 58 supports a plurality of accessories 60, each adapted to receive a piston 12 whose head 62 is to be coated using apparatus 10. Each attachment 70 includes a post 100 which extends radially outwardly from inner arrow 74 through a complementary opening that e is formed on the outer arrow 86. For simplicity and redundancy, in the preferred embodiment, the posts 100 themselves comprise radial extensions of several "second stop pins 96". Each post 10, like the anterior arrow 74, is preferably formed of an electrically conductive material such that it can be used to complete the electrical circuit between the rectifier 50 and the piston 12. In the preferred embodiment illustrated in Figure 2, the accessory 60 also includes a frame 102, mounted on the pole 100 near its base. The frame 102 which is preferably formed of a non-reactive polyurethane such as that sold under the trademark "Delrin ™", to support the piston 12 in order to prevent its rotation with respect to the post 100. In the preferred embodiment, an axial seal is formed at each circumferential end of the circumferential groove of the outer shaft 98. A coil spring 100 is located relative to the inner shaft 74 between the sleeve bearing 72 and the outer shaft 86, to axially bypass the outer shaft 86 relative to the inner shaft. 74 and in turn derive the second stop pin 96 to the detents. As a result, as long as the second stop pin 96 engages one of the detents, the outer arrow 86 will continue to move the inner arrow 74, notwithstanding the fact that the second stop pin 96 may be at the "wrong" end. of the slot 98. Of course, the second stop pin 96 will couple the detent in this manner only up to the time sufficient resistance is found for greater rotation of the inner arrow 74, as when the first stop pin 76 on the arrow inner 64 engages one end of the sleeve bearing circumferential groove 78. Upon finding this resistance, the second stop pin 96 will spring from the detent, and any further rotation of the outer shaft 86 will rotate only the outer shaft 86. The outer shaft 86 (and the inner arrow 74 there) in this way will be actuated by cam towards the front wall 22 of the electrocoating tank 14. The first stop pin 76 simultaneously cooperates with the circumferential notch of the sleeve bearing 78 to maintain the orientation of the inner arrow 74 and guide the piston 12 to its respective opening 20. Upon further insertion of the piston 12 into the opening 20, the second stop pin 96 will engage the retainer in the other end of the circumferential groove of the outer shaft 98, thereby holding the piston 12 within the opening 20. Figures 4 to 6 illustrate the various positions of the outer shaft 86, the inner shaft 74 / first stop pin 76 and the circumferential notch of the sleeve bearing 78. From the foregoing, it will be appreciated that the rotation of the outer shaft 86 initially produces pure rotation of the accessory 60 until the time when the first stop pin 76 engages the other end of the notch. circumferential of the sleeve bearing 78. And once the first stop pin 76 in this manner has engaged the end of the circumferential notch of the sleeve bearing 78, any further rotation of the outer arrow 86 will produce pure translation of the accessory 60 towards the front wall of the tank 22, to effect insertion of the piston 12 into the opening 20. To remove the piston 12 from the opening 20 after generating the desired coating, they reverse the insertion / restraint stages described above. Specifically, the operator will rotate the outer arrow 86 in the opposite direction (downward as illustrated in Figures 4 to 6) whereby the initial rotation of the accessory 60 / inner arrow 74 will be inhibited by contact between the piston 12 and the opening 20. As a result, the second stop pin 96 will spring from its detent at the end of the circumferential groove of the outer shaft 98. The outer shaft 86 will therefore rotate freely from the inner shaft 74 until the second stop pin 96 the opposite end of the circumferential groove of the outer shaft 98 engages. Meanwhile, the rotation of the outer shaft 86 imparts rotation to the cams 88, whereby the cams 88 exert a reduced force on the arrows 74, 86 and the springs 82 operate to translate the arrows 74, 86 back to the first ends 84, of the guide bearings 66, 68. Once the arrows 74, 86 have completely moved back to the first ends 84 of the guide bearings 66, 68, and the second stop pin 96 has engaged the other end of the circumferential groove of the outer shaft 98, any further rotation of the outer shaft 86 will also rotate the inner shaft 74 / accessory 60. The accessory 60 in this manner can rotating away from the electrocoating tank 14 to facilitate removal of the piston thus coated 12 from the present apparatus 10. Again with reference to Figures 4 to 6, in the preferred embodiment, the O-ring seal 24 used to seal each opening 20 With respect to the piston 12, the O-ring 24 itself is located within the opening 20 as against an internal flange 106. By inserting and axially advancing the piston 12 to the opening 20 with the actuator 58, the O-ring 24 is compressed axially between the periphery of the piston head 62 and the inner flange of the opening 106, thereby achieving a fluid-tight seal between the piston 12 and the opening 20. Accordingly, the head of the piston 62, and only its head 62 is placed in fluid communication with the interior of the electro-coating tank 14, while the opening 20 of another shape is sealed or "plugged" with the piston itself 12. The O-ring seal 24 in this manner performs the dual function of sealing the opening 20 relative to the piston 12 while effectively "masking" the work piece to allow only the electrolytic coating of a portion of its exposed surface. Finally, a brief discussion of the operation of the apparatus 10 once the pistons 12 have been clamped in their respective openings 20 in the electro-coating tank 12: with the openings 20 now "plugged" with the pistons 12, the electrocoating tank 14 is ready to receive different storage tank processing solutions 29, 30, 32, 34, as well as intermediate and final running water rinses. The solutions are selectively and sequentially directed by their dedicated pumps 36 from their respective storage tanks 29, 30, 32, 34 to the supply conduit 40. The supply conduit 40 in turn feeds the spray nozzles 44 placed inside the tank. of electrocoating 14 as opposed to the heads 62 of the pistons 12, whereby the solutions are sprayed onto the heads 62 of the pistons 12. After each solution is discharged from the electrocoating tank 14, compressed air can be directed through the electrocoating tank 14 and return supply conduits 40, 46 to increase its recovery (and to co-relatively normalize the temperature of the workpiece to avoid harmful condensation when removing the workpiece from the electrocoating tank 14. Depending on the particular processing solution, the electrocoating tank 14 can preferably also be rinsed with running water before directing another solution or separation of the work pieces of the electrocoating tank 14. When the sprayed solution is the electrolyte, the rectifier 50 is operated to apply current through electrolyte, with the piston 12, anode and the spray nozzles 44 as cathode. Meanwhile, by-products of gas and heat generated during electrolysis are transported from the electrocoating tank 14 and preferably back to the electrolyte storage tank 32 through the steam return / overflow conduit 46. Gas and heat products from the inside of the electro-coating tank 14 ensures superior quality and coating consistency. Still further, the hydrogen gas generated during electrolysis and vented from the electrocoating tank 14 may already be recovered in the electrolyte storage tank 32 or otherwise vented to the atmosphere at a remote site from the electrocoating tank 14, further promoting worker's safety Since the temperature of the piston 12 will probably rise above ambient temperature when the coated surface is sealed with hot water, there is little likelihood of condensation forming on the coated surface upon removal of the piston 12 from the electrocoating tank 14. However, if the sealing step is removed (making the last solution a neutralizing rinse with running water at room temperature) there is a much greater chance that the temperature of the coated surface will be below ambient when removing the piston 12 from the electrocoating tank 14, given the relatively low temperature of the electrolyte. Therefore, in accordance with another feature of the invention, heated air is circulated through the electrocoating tank 14 to normalize the temperature of the coated surface and thereby prevent this lateral condensation of ambient humidity upon removal of the pistons 12 from their respective openings 20.

While the preferred embodiment of the invention has been described, it will be appreciated that the invention is susceptible to modification without departing from the spirit of the invention or the scope of the appended claims. For example, while the invention has been described above in connection with anodized hard-coated aluminum piston, it will be appreciated that the apparatus 10 of the present invention is suitable for the electrochemical treatment of a variety of other metals, including titanium. and magnesium; and with a wide range of acid electrolyte / electrolyte temperatures.

Claims (20)

1. CLAIMS 1. An apparatus for simultaneously generating a first electrolytic coating a surface portion of each of at least two parts electrically conductive work, the apparatus characterized by comprising: a tank electrocoat including a wall having at least two openings formed there adapted to receive the workpieces, one of the workpieces, one of the openings, the tank further includes at least one electrode extending to the high-liner tank and one discharge; means for temporarily holding the work pieces in the openings to place their first surface portions in fluid communication with the interior of the tank; a seal for each of the openings with respect to each of the work pieces when each of the work pieces is fastened there, in such a way that only the first surface portion of each of the work pieces is placed in communication fluid with the inside of the electro-coating tank; means for directing an electrolyte to the tank, such that the electrolyte bypasses each of the work pieces in the electrode at least; and an energy supply connected to the workpieces and at least one electrode, respectively, to apply a current through the electrolyte in the tank to apply a current through the electrolyte in the tank when the electrolyte bypasses the workpieces and the at least one electrode, with which an electrolytic coating is generated in the first surface portion of each of the work pieces; and means for directing electrolyte to the electrocoat tank include a spray nozzle positioned within electrocoat tank opposed to the first surface portions of the workpieces when the workpieces are held in the openings.
2. 2. The apparatus according to claim 1, characterized in that the means for temporarily holding the workpieces in the openings include at least one accessory adapted to receive at least one of the work pieces; and an actuator mounted in the tank electrocoat to support the relative attachment to at least one of the openings, the actuator is operable to move relative accessory at least one of the openings, whereby at least one of the workpieces It is inserted inside and removed from at least one of the openings.
3. 3. The apparatus according to claim 2, characterized in that each of the work pieces is a piston; and wherein the accessory includes a post adapted to receive one of the pistons; and a frame to support one of the pistons to prevent its rotation with respect to the post.
4. 4. The apparatus according to claim 2, characterized in that the actuator is also operative to rotate the accessory with respect to at least one of the openings, whereby the placement of at least one of the work pieces in the accessory is facilitated. .
5. 5. The apparatus according to claim 2, characterized in that the actuator includes a pair of grooved bearings mounted in the electrocoating tank; one first arrow received in the slotted bearings, the first shaft is movable within the slotted bearings between a first position relative to the electrocoat tank and a second position relative to the electrocoat tank and a second position there; a spring in each of the bearings to derive the first arrow to the first portion; a cam plate mounted on each of the grooved bearings; a pair of cams carried by the arrow, each cam engages with one of the cam plates, respectively to move the arrows from the first position to the second position when the first arrow rotates; and where the accessory is supported by the first arrow.
6. 6. The apparatus according to claim 2, characterized in that the first arrow is hollow; and wherein the actuator includes a second arrow stamped with the first arrow, the accessory is connected to the second arrow.
7. 7. The apparatus according to claim 6, characterized in that the second arrow is moved by the first arrow; and includes stopping means in the second arrow to limit the rotation of the second arrow with respect to the bearings, whereby the rotation of the first arrow with respect to the bearings produces either pure rotation of the attachment with respect to the bearings when the first arrow is in the first position or move the accessory as the bearings move from the first position in the bearings to the second position.
8. 8. The apparatus according to claim 1, characterized in that it also comprises means for directing a rinsing fluid to the tank to rinse the first surface portion of each of the work pieces.
9. 9. The apparatus according to claim 1, characterized in that the means for directing the electrolyte to the electrocoating tank include a storage tank for storing an electrolyte supply, a supply conduit extending from the storage tank to the tank of the electrocoating, an operating pump for pumping the electrolyte stored in the storage tank through the supply conduit to the electrocoating tank and a first return conduit extending from the discharge of the electrocoating tank to the storage tank.
10. 10. The apparatus according to claim 9, characterized in that the electrocoating tank is sealed; and includes a second return conduit extending from the electrocoating tank to the storage tank, the second return conduit being connected to the electrocoating tank at a point above the normal operating level of the electrolyte.
11. 11. The apparatus according to claim 9, characterized in that it includes means in the storage tank to maintain the electrolyte at a desired temperature.
12. 12. The apparatus according to claim 1, characterized in that the workpieces act as anodes and at least some electrodes act as cathodes when applying the current through the electrolyte in the tank.
13. 13. A method for simultaneously generating a coating in a first surface position of each of at least two electrically conductive workpieces, the method is characterized in that it includes the steps of: fastening the work pieces in at least two openings that are they extend through a wall of an electrocoating tank, one of the workpieces to one of the openings, wherein the openings are adapted to sealably couple the work pieces by holding the work pieces in such a way that only the first surface portion of each of the work pieces is placed in fluid communication with the interior of the electro-coating tank; directing an electrolyte inside the electrocoating tank, the electrolyte bridges an electrode in the electrocoating tank and the first surface portion of each of the work pieces; apply a current through the electrolyte as the electrolyte bridges the work pieces and the electrode; discharge the electrolyte from the electrocoating tank; remove the work pieces from the openings; and spraying the electrolyte during the electrolyte direction stage.
14. 14. The method according to claim 13, characterized in that the step for directing the electrolyte includes a step of circulating the electrolyte between the electrocoating tank and an external storage tank in fluid communication with the electrocoating tank during the stage of current application.
15. 15. The method according to claim 13, characterized in that the method after the clamping step and before the electrolyte direction stage includes the steps of: directing a pretreatment fluid to the electrocoating tank. electrolyte from the group consisting of a cleaning solution, a deoxidizing solution, a caustic etching, an activating solution and water; and discharging the pre-electrolyte treatment fluid from the electrocoating tank.
16. 16. The method according to claim 13, characterized in that the electrolyte in the electrocoating tank is below the ambient temperature, the method further includes the step of heating the work pieces at room temperature before the removal step .
17. 17. - The method according to claim 13, characterized in that the electrolyte tank is sealed and wherein the method further includes the step of venting the electrocoating tank to a remote site of the electrocoating tank.
18. 18. The method according to claim 13, characterized in that it also includes, before the removal stage, the steps of directing a rinsing fluid to the electrocoating tank and discharging the rinsing fluid from the electrocoating tank.
19. 19. The method according to claim 18, characterized in that the method also after the stage of discharge of rinsing fluid and before the step of removing, includes the steps of: direct to the tank of electrorevestimiento a fluid of post treatment -electrolyte of the group consisting of a sealing solution, the solution containing a dye and a solution containing a dye and a solution containing a dry lubricant; maintaining the post-electrolyte treatment fluid in contact with the first surface portion of the work pieces for a pre-determined period of time; and discharging the post-electrolyte treatment fluid from the electrocoating tank.
20. 20. The method according to claim 19, characterized in that the method further includes the step of directing heated air to the electrocoating tank after the second discharge stage and before the removal step.