DE102015004746A1 - Method for extended coating of the cylinder liners of aluminum cylinder crankcases - Google Patents

Abstract

Method for the extended coating of the cylinder bores of aluminum cylinder crankcases, wherein the cylinder bores of the aluminum cylinder crankcase first finely spindles, then roughened and provided with a track coating by one of the methods chemical coating, electroplating, wire arc spraying, wire plasma spraying or powder plasma spraying. The method provides that the raceway coating (9) is made so that pores (4) form on its surface or that pores (4) are produced by an intermediate step in the manufacturing process and that the pores (4) are filled up by a subsequent process step become. For this purpose, it is provided that at least the cylinder bores of the cylinder crankcase (2, 2 ') are filled with a liquid coating material (5, 14), from the components chemically or electrochemically on the raceway coatings (9) of the cylinder liners are deposited and in that with the Coating material (5, 14) filled cylinder bores in each case a vibrating head (1, 1 ') is arranged, which vibrate at a predetermined frequency, vibration amplitude and for a predetermined period of time such that substantially all the pores (4) fill with the coating material.

Description

The invention relates to a method for extended coating of the cylinder liners of aluminum cylinder crankcases, wherein the cylinder bores of the aluminum cylinder crankcase initially finely spindled, then roughened and coated with a career coating according to one of the methods chemical coating, electroplating, wire arc spraying, wire plasma spraying or powder Plasma spraying is provided. It is also an object of the invention to provide an arrangement for carrying out the method.

The cylinder liners of internal combustion engines, especially those made of aluminum, are often provided with a protective layer which serves to increase the wear resistance. A variety of coating materials and methods have been proposed for coating. As wear protection layer, inter alia, a layer under the registered trademark "Nikasil" has become known, which consists of electrodeposited nickel-silicon carbide. However, it is also frequently the arc wire spraying with a spray wire, for example made of an iron alloy, applied for applying such a wear protection layer on the cylinder liners. Wire plasma spraying or powder plasma spraying are also known as coating methods.

Next it is from the DE 10 2010 043 527 A1 known to electroplate the cylinder surfaces of the crankcase of a motor with a bronze of copper and tin with a tin content of 18.5 wt .-% and boron carbide (B4C) as a dispersant. The coating method provides to arrange the crankcase on a coating plate, which is provided on the cylinder liners with an opening. Between the opening and the crankcase is a metal ring made of the same cast aluminum alloy as the crankcase. For sealing a liquid seal is arranged between the metal ring on the one hand and the coating plate and the crankcase on the other hand, wherein the crankcase and the metal ring form the cathode. The anode for electroplating consists of a bronze of 81.5 wt .-% copper and 18.5 wt .-% tin. For coating the cylinder of the crankcase is filled with the electrolytic bath liquid. On the cylinder surface of the crankcase and the metal ring, a bronze layer with a layer thickness of 150 microns is electrodeposited. The bronze layer is then honed to a layer thickness of 50 microns.

Common to the coating methods described above, that in particular pores and micro-defects in the coating can not be avoided. It therefore results in the production of an increased control effort and possibly a removal of the found to be insufficiently coated cylinder crankcase from the production process is inevitable.

From the GB 1 268 384 A It is also known to move in an electroless deposition of metal coatings, the parts of the assembly that should not be coated, such as the tub in which the coating is. For this purpose, a relative speed between liquid and surface not to be coated of greater than 0.9 m / s is proposed.

The DE 000069802367 T2 describes a plating method, for example, for plating printed circuit boards having micropores of a relatively small size of 20 to 50 μm. For plating, there is proposed as a concurrent measure: vibrationally stirring the treatment bath, conducting aeration in the treatment bath, pivoting the object to be plated, and applying a vibration to the object to be plated. The flow of the treatment liquid into the micropores should be averaged out. The vibrations of the individual components are generated by means of motors and amount to only a few hundred oscillations per minute.

Based on this prior art, it is an object of the invention to provide a method which makes it possible to improve the quality of cylinder liner coatings and thereby reduce the control effort in the production and to improve the throughput of the production line. It is also an object to provide an arrangement for carrying out the method.

The problem is solved by a method according to the main claim, advantageous developments are characterized in the dependent claims. An arrangement for carrying out the method is characterized in the independent claim 9, advantageous embodiments and further developments thereof in the claims dependent therefrom.

It has been found that the object can be advantageously solved by an extended method for coating the cylinder liners of aluminum cylinder crankcases, assuming that the cylinder bores of the aluminum cylinder crankcase first fining spindle, then roughened and optionally checked for voids and pores and after Test with a track coating according to one of the methods of chemical coating, electroplating, Arc wire spraying, wire plasma spraying or powder plasma spraying can be provided. The method according to the invention provides for the career coating to be carried out in such a way that pores are formed on its surface or that pores are produced by an intermediate step in the production process and that the pores are filled up by a subsequent process step. This happens because at least the cylinder bores of the cylinder crankcase are filled with a liquid coating material from the components chemically or electrochemically deposited on the coating of the cylinder liners and that in the filled with the coating material cylinder bores each a vibrating head is arranged, which with a predetermined Frequency, vibration amplitude and vibrate for a predetermined period of time such that to fill substantially all pores with the components to be separated.

It is particularly advantageous if the frequency extends into the ultrasound range, preferably up to greater than 45 kHz, most preferably greater than 30 kHz. Since the frequency, the oscillation amplitude and the duration of the oscillation vary with the coating material used, it is possible to cover a large variety of coating materials with the widest possible frequency range. The coating materials can be present as pure chemical solutions or colloidal solutions, the latter are therefore emulsions or dispersions. Of course, hybrids are also conceivable.

Furthermore, it may be advantageous to control the oscillating heads pulsed in each case, the pulse frequency being significantly lower than the frequency of the oscillation itself. The pulse frequency is preferably one order of magnitude smaller than the frequency of the oscillation.

The candidate coating materials are known in the art, some of which have already been explicitly mentioned in the introduction or are described in the cited prior art documents.

A property of the deposited constituents of the coating material should be preferred to reduce the dry friction. Starting from the base material, ie the aluminum alloy or the coating applied thereto, the person skilled in the art will select the suitable coating material with whose constituents the pores in the coating are to be filled. Frequency, duration of oscillation and oscillation amplitude depend heavily on the design conditions, in addition to the selected coating material. It is therefore necessary, starting from the selected coating material, for the respective design conditions, such as the dimensions of the respective cylinder bore and the dimensions of the respective oscillating head, the frequency, the duration of the oscillation, optionally their pulse frequency and the oscillation amplitude of the oscillating heads in experiments determine.

Explain the effect of the preferred attachment of the corresponding constituents of the coating material in the pores in that the coating material is placed in a non-directional movement by the oscillations of the oscillating head, which drives on the one hand, the components of the coating material to be deposited in the pores, which there in their Movement are inhibited, which favors an attachment and that on the other hand on the non-porous surface of the coating, a higher relative movement between the coating material and the surface to be coated prevails, which impedes an attachment.

Of course, it is also possible in addition to carry out the filling of the pores, by switching off the oscillating heads, a deposition on the entire surface of the cylinder bore in order to apply to the already existing coating another layer. By means of this extension of the method, the further layer in the first layer can be anchored over the filled-in pores so that a particularly good adhesion is achieved.

In an advantageous embodiment, the cylinder liner can be subjected to a heat treatment after the coating. The heat treatment can be carried out, for example, by means of a laser such that the surface of the respective cylinder bore is heated to a predetermined temperature. Of course, other known methods of heat treatment are applicable. The heat treatment achieves better homogeneity and better adhesion to the underlying layer.

Further, it is advantageous after the coating to perform a fine machining of the surface of the cylinder bore, this is preferably a honing process, most preferably a laser honing process.

The arrangement for carrying out the method advantageously provides a trough, in which the cylinder crankcase is lowered, wherein per cylinder bore a vibrating head is arranged. The oscillating heads can be arranged firmly in the tub and retract when lowering the cylinder crankcase in the cylinder bores.

Of course, there is also the alternative possibility to arrange the oscillating heads on a separate carrier. After lowering the cylinder crankcase in the tub, the oscillating heads can then be retracted by means of the separate carrier in the cylinder bores.

Advantageously, the oscillating heads are shaped so that, with filled coating material and operation of the oscillating heads, vibrations of the same intensity occur along the cylinder liners.

In a further embodiment, a liquid-tight seal can be provided for each cylinder bore, which seals the cylinder bores at least in the lowered state of the cylinder crankcase. The seal is designed so that after filling the cylinder bore with the coating material and retracted oscillating heads, only the cylinder liners are completely in contact with the coating material.

In a further embodiment of the arrangement can be provided that the tub is already filled with the coating material before lowering the cylinder crankcase, and that the coating material rises when lowering the cylinder crankcase in the tub, in the cylinder bores, such that when retracted oscillating heads and lowered Cylinder crankcase, the cylinder liners are completely in contact with the coating material.

Further embodiments and advantages of the invention will be explained in more detail with reference to the drawing, in which:

1 Schematic representation of a section of a cylinder bore with arranged therein oscillating head and filled coating material

2 Schematic representation of an arrangement for carrying out the method 1 the method and its mode of action will be explained in more detail. Shown there is a section of a cylinder bore with arranged therein oscillating head in section 1 , The cylinder bore is in a cylinder crankcase 2 made of aluminum and finely spindled in a previous processing step and with a raceway coating 3 been provided. On the wall surrounding the cylinder bore 13 of the cylinder crankcase 2 is the raceway coating 3 represented the pores 4 having. The pores 4 are thereby created controlled by the coating process itself or by a post-treatment step, such as by laser or by spark erosion. In the cylinder bore is as a coating material 14 a colloidal solution 5 , the particles 6 (in the drawing, only a few are shown) that contains in the pores 4 so that they are essentially filled out. For targeted deposition of the particles 6 in the pores 4 becomes the oscillating head 1 vibrated as indicated by the movement arrow 7 is indicated. The from the oscillating head 1 generated vibration sets the colloidal solution 5 and with it the particles 6 in a non-directional motion, as indicated by the directional arrows 8th is indicated. The undirected motion becomes part of the particle 6 in the pores 4 crowded. Once in the pores 4 reached, reduces the mobility of the particles 6 drastically, so that these attach themselves to the walls of the pores 4 can attach. The movement of the particles 6 outside the pores 4 on the other hand remains large, so that an attachment of the particles 6 at the non-porous areas of the track coating 3 is at least made more difficult.

By way of derogation from the example chosen, if the coating material is to be a solution from which ions are to be deposited in the pores, this is done in the same way as described above with regard to the particles.

As already stated above, the frequency, amplitude and duration of the vibration of the oscillating head depend 1 of several parameters. Of particular importance in this case are the coating material itself, ie in the example the colloidal solution used 5 and the geometry of the arrangement. Due to this dependency, the appropriate parameters of the oscillation are to be determined case by case in test series. For this purpose, it is advantageous if the frequency range of the oscillating head, as well as its oscillation amplitude, can be varied within wide ranges. It has proved particularly advantageous if the frequency of the oscillating head extends into the ultrasonic range, preferably greater than 20 kHz, most preferably greater than 45 kHz.

By choosing the oscillating head as a vibration generator can be superimposed by its pulsed switching on and off the actual oscillation very easily a low-frequency oscillation, which may be advantageous for the targeted deposition of the particles in the pores.

Should not only the pores through the coating process 4 are filled, but beyond a further layer (not shown) are deposited on the cylinder bore, is a relative movement between the particles 6 and the raceway coating 3 for a deposit rather obstructive, so that in this case the vibration of the oscillating head 1 preferably switch off, but at least reduce it.

To strengthen the deposits in the pores 4 it may be necessary or at least advantageous, the accumulated particles 6 to undergo a heat treatment. This is the colloidal solution 5 optionally, the cylinder head is washed, dried and heat-treated at least in the region of the cylinder bore. For this purpose, all known methods of heat treatment come into question, for example also the use of a laser beam.

Is the process of filling in the pores 4 , or possibly the application of a further layer (not shown) completed, may be another finishing step of the cylinder liner 9 connect. This is usually a honing process. Here it makes sense to use the laser honing method.

As indicated above, nothing changes in the procedural approach when the coating material is substituted for the colloidal solution described above 5 is a pure chemical solution, from the ions in the pores 4 to be separated, only the process parameters are different.

Having explained the principle of the method in its basic features, an arrangement will now be presented below which allows the method to be carried out. Again, the arrangement is described only in principle, the expert but it is thus possible to adapt just this principle to its specific application.

2 shows a simplified representation of a tub 10 in sectional view into which a cylinder crankcase 2 ' as by the double arrow 12 indicated, lowered. The cylinder crankcase 2 ' is also shown cut, the cylinder bores point down. The cylinder crankcase 2 ' resting on a support 11 , on the oscillating heads 1' are fixed, such that they project centrally into the cylinder bores. Between the wall surrounding the cylinder bores 13 of the cylinder crankcase 2 ' and the vibrating heads 1' is the coating material 14 that about the carrier 11 penetrating pipe feeds 15 and a manifold 16 from a storage container 17 by means of a pump 18 is supplied. In the area of the support surface 19 located between the cylinder crankcase 2 ' and the carrier 11 a seal (not shown), which the pipe inlets 15 leaves free. The oscillating heads 1' are via oscillating head feed lines 20 with a control device 21 connected via line 22 also the pump 18 controls.

The arrangement described above is operated as follows: First, the cylinder crankcase 2 ' with the cylinder bores down into the tub 10 lowered so that the cylinder crankcase 2 ' with the interposition of the seal (not shown) on the support surface of the carrier 11 comes to stand. The seal consists of a against the coating material 14 resistant, elastic material, so that the sealing effect by the weight of the cylinder crankcase 2 ' comes about. Is the cylinder crankcase 2 ' lowered, the cylinder bores are sealed down and the oscillating heads 1' retracted centrally into the cylinder bores. In the next step, the coating material 14 from the reservoir 17 by means of the pump 18 controlled by the control device 21 , into the manifold 16 promoted and rises above the pipe feeds 15 in the free spaces of the cylinder bores. Are the cylinder bores with the coating material 14 filled so far that the entire cylinder bore of each cylinder is in contact with the coating material controls the controller 21 the oscillating heads 1' with a predetermined frequency and amplitude for a likewise predetermined time. After expiry of the predetermined time, the control unit switches 1 the oscillating heads and pumps by means of the pump 18 , optionally after a lapse of a second period of time, the coating material 14 from the cylinder bores in the reservoir 17 back. In this case, the pumped back coating material 14 if necessary, go through a reprocessing station (not shown). After removing the coating material, the cylinder crankcase 2 ' from the tub 10 taken off, optionally washed, dried and fed to the next processing step.

Of course, there are a variety of alternative design options for the arrangement described above. So it is possible the carrier 11 out 2 form trough-like and the pipe feeds 15 to modify that they are only trained in the carrier risers. In this case, the in 2 shown tub 10 down tight and the manifold 16 and the reservoir 17 would be omitted.

In this alternative embodiment of the arrangement, the tub would be constantly filled with the coating material and the trough-like support for the cylinder crankcase would be designed to be movable, so that he removed the tub, fitted with the cylinder crankcase, and could be returned to the tub. When returning the trough-like support, the coating material would rise in the riser pipes and fill the cylinder bores.

Of course, there is also the possibility, in deviation to 2 to form the carrier with the tub in one piece.

A further modification could provide that the oscillating heads are retracted from above into the cylinder bores. This would, in a modification of the example after 2 to provide a carrier, on the underside of the oscillating heads are arranged. The carrier would then be shown in the figure 2 lowered from above in the presentation and thus retracted the oscillating heads from above into the cylinder bores.

As the alternative exemplary embodiments described above show, there are numerous possibilities of modification in the configuration of an arrangement for carrying out the method according to the invention. Allen configurations together is the arrangement of the oscillating heads in the cylinder bores of the cylinder crankcase, centered to the cylinder bore axis.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102010043527 A1 [0003]
• GB 1268384A [0005]
• DE 000069802367 T2 [0006]

Claims (14)

Method for the extended coating of the cylinder bores of aluminum cylinder crankcases, wherein the cylinder bores of the aluminum cylinder crankcase first fine-spindles, then roughened and provided with a track coating by one of the methods chemical coating, electroplating, wire arc spraying, wire plasma spraying or powder plasma spraying, characterized in that the track coating is carried out in such a way that pores ( 4 ) or that pores ( 4 ) are produced by an intermediate step in the production process and that by a subsequent process step the pores ( 4 ), in that at least the cylinder bores of the cylinder crankcase ( 2 . 2 ' ) with a liquid coating material ( 5 . 14 ) from which constituents are chemically or electrochemically deposited on the raceway coatings of the cylinder liners ( 9 ) are separable and that in the with the coating material ( 5 . 14 ) filled cylinder bores in each case one oscillating head ( 1 . 1' ), which vibrate at a predetermined frequency, oscillation amplitude and for a predetermined period of time such that substantially all the pores ( 4 ) with the components to be separated. A method according to claim 1, characterized in that the frequency extends into the ultrasonic range, preferably up to greater than 20 kHz, most preferably to greater than 45 kHz. Method according to claim 1 or 2, characterized in that the oscillating heads ( 1 . 1' ) are pulsed on and off, such that the frequency of the respective oscillating head ( 1 . 1' ) is superimposed on a low-frequency pulse frequency. Method according to one of the preceding claims, characterized in that the cylinder liners ( 9 ) are subjected to a heat treatment after coating. A method according to claim 4, characterized in that the heat treatment by means of laser is such that the surface of the cylinder liners ( 9 ) are heated to a predetermined temperature. Method according to one of the preceding claims, characterized in that after the coating, a fine machining of the surfaces of the cylinder liners ( 9 ) he follows. A method according to claim 6, characterized in that the fine machining is a honing process. A method according to claim 7, characterized in that the honing process is a laser honing process. Arrangement for carrying out the method according to one of the preceding claims, characterized in that for carrying out the coating process, a trough ( 10 ) is provided, in which the cylinder crankcase ( 2 . 2 ' ) is lowered and that per cylinder bore a vibrating head ( 1 . 1' ) is arranged. Arrangement according to claim 9, characterized in that the oscillating heads ( 1 . 1' ) are fixed in the tub and when lowering the cylinder crankcase ( 2 . 2 ' ) into the cylinder bores. Arrangement according to claim 9, characterized in that the oscillating heads ( 1 . 1' ) on a separate carrier ( 11 ) are arranged and after lowering the cylinder crankcase ( 2 . 2 ' ) in the tub ( 10 ), are retracted into the cylinder bores. Arrangement according to one of claims 9 to 11, characterized in that the oscillating heads ( 1 . 1' ) are shaped so that when filled coating material ( 5 . 14 ) and operation of the oscillating heads ( 1 . 1' ) along the cylinder liners ( 9 ) Vibrations of the same intensity occur. Arrangement according to one of claims 9 to 12, characterized in that a liquid-tight seal is provided for each cylinder bore, these at least in the lowered state of the cylinder crankcase ( 2 . 2 ' ) seals so that the cylinder bore with the coating material ( 5 . 14 ) is fillable so that when retracted oscillating heads ( 1 . 1' ) the cylinder bore in the region of the cylinder bore ( 9 ) completely with the coating material ( 5 . 14 ) is in contact. Arrangement according to one of claims 9 to 13, characterized in that the trough ( 10 ) before lowering the cylinder crankcase ( 2 . 2 ' ) already with the coating material ( 5 . 14 ) and that the coating material ( 5 . 14 ) when lowering the cylinder crankcase ( 2 . 2 ' ) in the tub ( 10 ) rises in the cylinder bores, such that when retracted oscillating heads ( 1 . 1' ) and lowered cylinder crankcase ( 2 . 2 ' ) the cylinder bores in the region of the cylinder liners ( 9 ) completely with the coating material ( 5 . 14 ) are in contact.

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