EP1557223B1 - Process for treating of cast aluminium parts - Google Patents

Description

The invention relates to a method for the treatment of aluminum castings according to the preamble of patent claim 1.

Aluminum castings as they are used, for example, as a cylinder crankcase, cylinder head or the like. In internal combustion engines learn about their life cycle by surface stresses, temperature effects, etc., especially on their outer sides optical quality impairments. The latter can at least be reduced by targeted surface treatments.

From the DE 43 03 339 C2 discloses a method for treating aluminum die cast parts prior to the application of a porous catalytic coating. These castings are degreased, subjected to blasting and provided in deionized water at temperatures between 90 ° and 100 ° C in 0.5 to 1 hour with a 0.5 to 1Nm thick boehmite layer.

The DE 198 47 063 A1 deals with a method for cleaning automotive parts with corroded and / or contaminated by burned oil and grease residues surfaces. For this purpose, the motor vehicle parts are processed in multiple stages, such that the pre- and / or basic cleaning is done by a vibratory finishing process and the finishing by high-pressure water.

The US 5,588,901 deals with the supply of sodium bicarbonate particles to a jet nozzle, using compressed air or water to bring these particles into contact with a surface to be cleaned.

The US 5,681,205 which is considered to represent the closest prior art to the subject-matter of claim 1 describes the cleaning of a metal surface by irradiation with a wet agent containing sodium bicarbonate and a corrosion inhibitor as the abrasive agent.

The object of the invention is to provide a method for the treatment of aluminum castings, preferably for internal combustion engines, through which the surfaces of these aluminum castings receive a high quality level. However, it should also be ensured that the process is economically feasible.

According to the invention, this object is solved by the features of patent claim 1. Further, the invention ausgestaltende features are included in the subclaims.

The main advantages achieved by the invention can be seen in the fact that the treatment of the aluminum castings by means of the first and the second high pressure wet blasting to high quality surfaces on said aluminum castings, the latter is still supported by targeted rinsing, preserving and drying. The applied method largely prevents residual particles of the aluminum castings from causing malfunctions. The medium that is used for the first high-pressure wet blasting consists of a mixture of water and salt crystals, for example potassium sulfate and soda, which act in an abrasive manner on the surfaces of the aluminum castings. In other words, by gently removing oxide layers, pronounced soiling and deep-seated efflorescence are eliminated, but without causing material removal or damage. With the second high-pressure wet blasting, in which water is used without the addition of solid media, insides of the aluminum castings of oil-grease residues and the sealing surfaces of deposits e.g. made of silicone. The remaining blasting agent residues are dissolved by an aqueous blasting process of the aluminum castings, wherein the medium used here will add a liquid preservative. In addition, the aluminum castings are put into a final state by drying by means of a suitable device which can be operated with compressed air but avoiding drying spots. After all, the media for high-pressure wet blasting because natural products can be easily disposed of

In the drawing, an embodiment of the invention is shown, which will be described in more detail below.

Fig. 1

eine schematische Brennkraftmaschine mit Aluminiumgussteilen, die mit dem Verfahren nach der Erfindung behandelt werden;

Fig. 2

eine Einrichtung zur Durchführung des Verfahrens;

Fig. 3

ein Diagramm über den Ablauf des Verfahrens.

Show it

Fig. 1

a schematic internal combustion engine with aluminum castings, which are treated by the method according to the invention;

Fig. 2

a device for carrying out the method;

Fig. 3

a diagram of the procedure of the procedure.

An internal combustion engine 1 includes aluminum castings 2 and 3 each having an outside As and an inside Is formed by a cylinder crankcase and a cylinder head. Other aluminum castings of the internal combustion engine 1 are a valve cover 4, a crankshaft bearing bridge 5 and an oil pan 6. On the internal combustion engine 1, a crankshaft 7 and camshafts 8 and 9 are also provided.

For treating the surface of the outside As and the inside Is of the aluminum castings 2 and 3, a method is used in which first the outside As is treated with a first high-pressure wet-blasting and then the inside Is by means of a second high-pressure wet blasting, this second High-pressure wet blasting without the addition of solid media. Following this, the cast aluminum parts are rinsed, preserved and dried. In the first high-pressure wet blasting, a medium of a mixture of water and salt crystals is used, for which potassium sulfate - K 2 SO 4 - and coarse-grained soda - Na 2 CO 3 - are used.

The mixing of the water with the potassium sulfate or the soda, ie the salt crystals, takes place in an injection device 10, the supply lines 11 and 12 for water and the potassium sulfate and soda. Both supply lines 11 and 12 open into a mixing chamber 13, which is followed by a nozzle 14. The media potassium sulfate and soda can be fed dry or as a slurry, and The water, which is irradiated under high pressure up to 1000 bar, a suitable rust inhibitor can be added.

For rinsing the aluminum castings 2 and 3, an aqueous jet process is used, in which blasting process the water can be added a liquid preservative. It is also conceivable in this context that after rinsing the aluminum castings 2 and 3 are introduced into an immersion bath.

1. 1. Schritt: Behandlung der Außenseite As der Aluminiumgussteile 2 und 3 durch Hochdruck-Nassstrahlen mit einem Medium, das zumindest Kaliumsulfat enthält,
2. 2. Schritt: Behandlung von Dichtflächen und der Innenseite Is der Aluminiumgussteile 2 und 3 mit Hochdruck-Nassstrahlen,
3. 3. Schritt: Spülen und Konservieren der Aluminiumgusssteile 2 und 3,
4. 4. Schritt: Trocknen der Aluminiumgussteile 2 und 3.

In addition, it is recommended that the following process steps be used to carry out the process for the treatment of cast aluminum parts:

1. 1st step: Treatment of the outside As of the aluminum castings 2 and 3 by high-pressure wet blasting with a medium containing at least potassium sulfate,
2. 2nd step: Treatment of sealing surfaces and the inside Is of the aluminum castings 2 and 3 with high-pressure wet blasting,
3. 3rd step: rinsing and preserving the aluminum castings 2 and 3,
4. 4th step: Dry the aluminum castings 2 and 3.

Finally, the method can be further improved if, after rinsing and preserving the aluminum castings 2 and 3, they are introduced into a dipping bath Tb

Claims (8)

1. Process for treating cast aluminium parts (2, 3) having an outer side (As) and having an inner side (Is), preferably for internal combustion engines (1), in which the cast aluminium parts (2, 3) are machined by means of blasting, wherein initially the outer side (As) of the cast aluminium parts (2, 3) is treated by means of a first high-pressure wet blasting process and then the inner side (Is) of the cast aluminium parts (2, 3) is treated by means of a second high-pressure wet blasting process, wherein the cast aluminium parts (2 and 3) are subsequently rinsed, preserved and dried, and wherein a medium composed of a mixture of water and salt crystals is used for the first high-pressure wet blasting process.
2. Process according to Claim 1, characterized in that the mixture of the medium comprises potassium sulphate and sodium carbonate.
3. Process according to Claim 1, characterized in that water without the addition of solid media is used for the second high-pressure wet blasting process.
4. Process according to Claim 1, characterized in that the cast aluminium parts (2, 3) are rinsed using an aqueous blasting process.
5. Process according to Claim 4, characterized in that a liquid preservative is added to the blasting process medium.
6. Process according to Claims 4 and 5, characterized in that the rinsing and preservation processes are followed by the cast aluminium parts being immersed in a dipping bath.
7. Process according to Claim 1, characterized by the following process steps:

   Step 1: Treating the outer side (As) of the cast aluminium parts (2 and 3) by high-pressure wet blasting using a medium that contains at least potassium sulphate,

   Step 2: Treating sealing faces and the inner side (Is) of the cast aluminium parts (2 and 3) by high-pressure wet blasting,

   Step 3: Rinsing and preserving the cast aluminium parts (2 and 3),

   Step 4: Drying the cast aluminium parts (2 and 3).
8. Process according to Claim 7, characterized in that the cast aluminium parts (2, 3) are placed in a dipping bath after step 3.

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