DE102011087575A1 - Producing composite component coated with friction layer, comprises providing a light-metal surface of a molded blank by a thermal spraying with the friction layer, where the light-metal surface is provided with projections during molding - Google Patents

Abstract

The method comprises providing a light-metal surface (5) of a molded blank (2) by a thermal spraying with a friction layer, where the light-metal surface is provided with projections (6) during molding, and the projections have an undercut in which a wear-resistant layer engages for connecting the light-metal surface. The projections are designed as pin-like elevations during the molding and distributed in a uniform spacing from each other via the surface to be coated, where the undercuts are introduced downstream in the projections during a molding step and a thermal spraying step. The method comprises providing a light-metal surface (5) of a molded blank (2) by a thermal spraying with a friction layer, where the light-metal surface is provided with projections (6) during molding, and the projections have an undercut in which a wear-resistant layer engages for connecting the light-metal surface. The projections are designed as pin-like elevations during the molding and distributed in a uniform spacing from each other via the surface to be coated, where the undercuts are introduced downstream in the projections during a molding step and a thermal spraying step. The undercuts: are produced by material deposition and/or plastic deformation; are rotationally symmetrical to a longitudinal central axis of the elevations; and are formed in a mushroom-shape manner. The projections are formed in cylindrical, quadratic, frustum of pyramid or frustoconical shape manner and formed upward and/or away from an aluminum surface. An independent claim is included for a composite component.

Description

The invention relates to a method for producing a coated with a friction layer composite component in which a light metal surface of a cast blank is provided by thermal spraying with a friction layer and the light metal surface is provided with projections which arise during casting, wherein the Projections have an undercut, in which engages the wear-resistant layer for connection to the light metal surface, and a corresponding component.

In order to save fuel in modern motor vehicles, it is known to use aluminum parts to save weight. In particular, such aluminum parts are often used for the replacement of cast iron or steel parts in vehicles. In particular, it is known to use aluminum parts for brake drums and brake discs. However, aluminum has the disadvantage that it is relatively soft. Therefore, the aluminum parts are provided on their surface with a wear-resistant layer. Such wear-resistant layers in brake discs, etc. must not only have a high wear resistance, but also have a high temperature stability, thermal conductivity and good adhesion to the aluminum and not least machinable and may not "flake" due to thermal stresses from the aluminum base ,

Therefore, it is currently being attempted to provide such aluminum brake discs by coating by means of thermal spraying with correspondingly wear-resistant layers.

From the US 6,290,032 B1 It is therefore known to provide an aluminum part with a groove pattern on its surface by thermal spraying with a wear-resistant ceramic layer. It is assumed according to column 3, lines 60-67 that the tips of the grooves during thermal spraying partially melt and form undercut hooks that fix the coating on the aluminum surface. Alternatively, it is stated that such undercut hooks could be introduced into the grooves by subsequent machining.

However, that's how it turns out 3B results, only possible, to achieve the uniform geometry shown there, if the thermal spraying takes place in a corresponding angle to the surface to be coated, namely in the picture from the right. Then, if necessary, the illustrated undercut hooks could arise from the groove tips. However, it is then again difficult to fill the valleys, since the injected material has to be introduced into the grooves virtually around the corner. Thus, gaps may arise, which in turn make the discs useless because they can lead due to the "material error" to increased wear to the uselessness of the brake discs, etc.

In contrast, the object of the present invention is to provide a way with which on the one hand a thermally sprayed coating adheres firmly to a light metal surface and on the other hand allows a complete coating of the light metal surface.

This object is achieved by the method set forth in claim 1 and Komopsit component according to claim 6.

Since, according to the inventive method, the protrusions are formed as a pin-like protrusions during casting and are distributed uniformly spaced over the surface to be coated, wherein the undercuts are introduced into the protrusions in a step downstream of the casting and the thermal spraying step is it is possible to firmly bond the friction layer applied by thermal spraying with the light metal surface of the molded blank of the composite component. In this case, the sprayed material can reach all areas of the light metal surface, since the pin-like elevations do not hinder a "distribution". Also, unlike the prior art, there is no preferred angle or direction for thermal spraying depending on the undercuts. In addition, the pin-like elevations allow easy removal of the cast blank.

The term "composite component" is understood here to mean a component for a motor vehicle which consists of materials having different properties, which are advantageously combined with one another in order to optimize weight, strength, vibration behavior, corrosion or wear properties or the like and / or to lower them To reach production costs. In particular, these are components that consist of a light metal (such as aluminum or magnesium) or their alloys and that are provided with a coating of a different material, preferably by thermal spraying.

The methods of thermal spraying are surface coating methods. Loud DIN EN 657 In this case, filler materials, the so-called spray additives, inside or outside a spray burner off, on or melted, accelerated in a gas stream in the form of spray particles and thrown onto the surface of the component to be coated. The component surface is thereby not melted (as opposed to build-up welding) and only subjected to a low thermal load. A layer formation takes place because the spray particles flatten more or less depending on the process and material when hitting the component surface, stick primarily by mechanical clamping and layer by layer build up the spray layer. Quality features of sprayed coatings are low porosity, good adhesion to the component, freedom from cracks and homogeneous microstructure. The achieved coating properties are significantly influenced by the temperature and the speed of the spray particles at the time of their impact on the surface to be coated. The surface condition (purity, activation, temperature) also has a significant influence on quality features such as adhesion.

As an energy source for the on or melting of the spray additive used electrical arc (arc spraying), plasma jet (plasma spraying), fuel-oxygen flame or fuel-oxygen high-speed flame (conventional and high-speed flame spraying), fast, preheated gases (cold gas spraying ) and laser beam (laser beam spraying).

The purpose of the thermal spraying is in the present case the coating of the Leichmetallbauteils with a hard and abrasion resistant friction layer, preferably of oxide ceramic and carbide materials.

Advantageously, the plasma spraying of steel with embedded iron oxides is carried out in the present case.

As a pin-like projections projections from the surface of the blank are considered, the longitudinal extent (elevation) is longer than their dimensions in width. Preferably, the longitudinal extent is more than twice as large as that in the width. It is particularly preferred if the elevations are regularly formed, i. have a longitudinal central axis. In particular, the elevations are equally spaced from each other, so that there is a good distribution of holding forces to each other.

Depending on the need, the cast blank can be processed prior to thermal spraying, in particular the surface can be treated to prepare the thermal spraying, z. B. by corundum.

It is particularly preferred if the undercuts are produced by material removal, such as milling, turning, laser cutting, etching, or plastic deformation.

In a preferred variant, the undercuts are made approximately rotationally symmetrical to the longitudinal central axis of the pin-like elevations. Most preferably, a mushroom-head shape (i.e., T-shaped in section) is used. Hereby, a particularly good adhesion of the thermal spray coating and, at the same time, a particularly good gapless distribution of the coating can be obtained.

The pin-like projections can be formed with a cylindrical, square, truncated pyramid or truncated cone-like shape.

A particularly easy demolding of the cast blank is obtained when the pin-like elevations are formed upward or tapering away from the aluminum surface.

The inventive method is particularly suitable for producing a composite component in which a light metal surface of a cast blank is provided with a wear-resistant applied by thermal spraying friction layer and the light metal surface has projections which have an undercut, in which the wear-resistant friction layer engages for connection to the aluminum surface, wherein the projections are formed as pin-like projections and distributed at a uniform distance from each other over the surface to be coated.

This results in the advantages already mentioned above.

Preferably, the undercuts in approximately rotationally symmetrical to the longitudinal central axis of the pin-like elevations. In particular, a mushroom shape has been found to be particularly effective in fixing the friction layer.

In this case, a particularly good and uniform coating is achieved when the pin-like elevations are approximately perpendicular to the surface to be coated.

Preferably, the blank is made of aluminum or magnesium.

The invention is particularly suitable for use in a composite component, in particular for a motor vehicle, and very particularly preferably as a friction disk, in particular brake disk, transmission or clutch disk of a motor vehicle.

In contrast to the known two-piece brake discs (support pot made of aluminum, rest of steel) further optimization is possible because the unsprung masses are further reduced and also the heat dissipation is higher.

Further details, features and advantages of the invention will become apparent from the following description of an embodiment with reference to the drawing, in which

1 shows a schematic perspective view of a portion of a brake disc;

2 a section of a cross section through the 1 along the line II and

3 a cross section through the brake disc 1 along the line II in the coated state.

In the figures one is as a whole with 1 designated composite brake disc shown.

This consists of a cast blank 2 made of aluminum, on which a friction layer 3 to provide the actual braking surface 4 is applied.

Thus on the light metal surface 5 of the cast blank 2 The friction layer can be applied and fixed by thermal spraying is the surface 5 with projections 6 provided during casting and undercuts 7 obtained in a later step.

The projections 6 are formed as a pin-like projections and at a uniform distance from each other on the surface to be coated 5 distributed.

They are for better releasability of the blank 2 after casting upwards or from the aluminum surface 5 formed tapering away and have a substantially truncated cone shape or the shape of a truncated rotational hyperboloid.

The undercuts 7 be in the projections 6 introduced in a step downstream of the casting and the thermal spraying step upstream. The undercuts 7 allow the later sprayed friction layer a mechanical fixation on the surface 5 of the blank 2 ,

The undercuts 7 are approximately rotationally symmetrical to the longitudinal center axis of the pin-like elevations 6 executed and have a mushroom head shape with respect to the shaft 8th widened head nine on (cf. 3 ).

The undercuts 7 are in the present case produced by plastic deformation, z. B. by upsetting or rolling over, quasi-known as riveting, so that the head nine vigorously mushroomed.

So it will be the blank first 2 of aluminum incl. the projections 6 cast and these are processed after removal from the mold to the undercuts 7 manufacture.

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

• US 6290032 B1 [0004]

Cited non-patent literature

• DIN EN 657 [0010]

Claims (10)

A method for producing a friction-coated composite component in which a light-metal surface of a cast blank is provided with a friction layer by thermal spraying and the light-metal surface is provided with protrusions formed during casting, wherein the protrusions have an undercut in which engages the wear-resistant layer for connection to the light-metal surface, characterized in that the projections are formed during casting as a pin-like projections and are evenly spaced over the surface to be coated distributed, the undercuts in the projections in a The step downstream of the casting step and the thermal spraying step are introduced. A method according to claim 1, characterized in that the undercuts are produced by material removal and / or plastic deformation. A method according to claim 1 or 2, characterized in that the undercuts are performed approximately rotationally symmetrical to the longitudinal central axis of the pin-like elevations and in particular have a mushroom-head shape. Method according to one of the preceding claims, characterized in that the pin-like elevations are formed with a cylindrical, square, truncated pyramid or truncated cone-like shape. Method according to one of the preceding claims, characterized in that the pin-like elevations are designed to taper upwards or away from the aluminum surface. Composite component, in particular obtainable by a method according to one of claims 1 to 5, wherein a light metal surface of a cast blank is provided with a wear-resistant applied by thermal spraying friction layer and the light metal surface has projections having an undercut, in which engages the wear-resistant friction layer for connection to the aluminum surface, characterized in that the projections are formed as pin-like elevations and distributed at a uniform distance from each other over the surface to be coated. Composite component according to claim 6, characterized in that the undercuts have approximately rotationally symmetrical to the longitudinal central axis of the pin-like elevations, and in particular have a mushroom head shape. Composite component according to claim 6 or 7, characterized in that the pin-like elevations are approximately perpendicular to the surface to be coated. Composite component according to one of claims 6 to 8, characterized in that the blank made of aluminum or magnesium. Use of a composite component according to one of claims 6 to 9 as a friction disk, in particular as a brake disk or clutch disk.

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